Strange coolant leak location and a front diff fluid leak out of vent tube...

[DP96XLT]

Hey guys, I haven't posted in a while because, quite frankly, everything else in life has gone to hell, but I digress...

In the past two years we have put almost 17k miles on the 42k mile "survivor" 1996 Ford Explorer XLT. As a quick recap we redid just about everything about two years ago. New cooling system (everything but the heater core), new synthetic fluids everywhere (including the diffs), new brakes (hoses, calipers, rotors, pads), new shocks, new front end suspension components, etc, etc...

When I redid the cooling system I used an Autozone radiator, thinking that if I have problems it is a quick swap-out because of the lifetime warranty. Well, wouldn't you know it I ended up having a coolant leak and was trying to figure out exactly where it is coming from. It was leaking on the drivers side front of the engine dripping down the side of the block in the front corner from above. In looking there isn't any bolts that go into the cooling system and the waterpump was brand new 2 years ago (motorcraft) along with everything else. None of the cooling hose clamps were loose and I couldn't see above because of the A/C and power steering brackets. But after a bunch of research I figured it was one of two things, either a freeze plug (highly unlikely as there is virtually no rust on the engine at all, just surface rust with teh age and no rust on the freeze plugs), or it is the intake manifold gaskets (I couldn't believe the design when I saw what Ford used from the factory, literally a paper gasket with a small embossed silicone bead). Given the age and everything else I figured it had to be the intake manifold gasket, but still went investigating.

I noticed the coolant was down in the reservoir and it was above an inch or two down in the radiator, so I filled everything back up and then started it from cold and let it pressurize. Well, wouldn't you know it but before it does I see it squirt coolant out of the passenger side radiator end tank at the seal where the end tank is crimped to the core. That is on the opposite side of the engine bay and couldn't account for the coolant seen on the drivers side.

So, considering I have to replace the radiator I figure I would also do a coolant bypass at the heater core valve. Ever since I did the cooling system a couple of years ago I noticed that if you have the heat on the coolant temp would go way up and then drop way down when the thermostat opened. I used a Motorcraft OEM thermostat and it works properly just that there is no "bypass" hole in the thermostat outside of the ball-valve that allows you to bleed the system properly (which closes under pressure). I also noticed that the coolant hose on the passenger side at the top of the engine gets a bunch of pressure when the temp shoots up and it relieves when the thermostat opens. I am sure that is why the end-tank on the radiator popped a seal and it can't be good for the cooling system as a whole to be quick-cycling like that in winter.

Now, while I was waiting for the radiator (*******s at Autozone made me order a replacement since they no longer carry them in stock, which I will get refunded when I return the bad one), I put on a "known bad" radiator cap that won't hold pressure and noticed no more leaks in the cooling system, either from the radiator end tank seal or the drivers side.

Now, I know the factory "fix" was a coolant bypass that utilized the cooling system temp sensor for the gauge as a bypass point that used a 3/8" line and ran from that point down to the intake hose just before the waterpump. I would gladly utilize the same kit if it was available, but alas, it is not. Piecing together a "kit" also seems like a major PITA considering that I would need to source a tee for the temp sensor as well as a tee for the big hose and all that jazz. Also considering that a 5/8" heater hose seems to do a good job when the heater bypass valve is in bypass mode in the summer I figure the only real issue is a reduced amount of coolant flow through the heater core compared to it being bypassed. So I picked up two 5/8" x 3/8" metal tees ($20 each on amazon) but I had to drill out the inside since they necked down quite a bit on the core of them. I will put on just before the heater core bypass valve and loop the 3/8" sides together and that should give an "escape path" for the extra coolant that is not going to run through heater core (also, as a side note, the heater core is perfect on the inside, I scoped it and there is not corrosion or debris plugging it, it just doesn't flow as well as a 5/8" hose and I get GREAT heat out of it). I figure I will still get plenty of coolant flow through the core in doing this. I will also reverse the hoses at the core to make sure it stays "clear".

Does this seem like a reasonable and valid way of dealing with the bypass issue?

Should I also drill a small hole in the thermostat (or basically just remove the ball "valve" to allow it to mix coolant as well)?

Lastly, Should I also do the intake gasket as well when I do the radiator? Or do I get it all back together with the bypass and thermostat hole and see if the extreme pressure was causing the leak and if it doesn't leak at all I am good? (Hey, I gotta be honest, having time to do the intake manifold is something I really don't have given what is on my plate right now, I mean I am a totally "pro-active" person in taking care of issues, but is there ANY chance it was a pressure based issue and without extreme pressure spikes I will be "OK"?)

Next issue is the fact that after I redid the fluids in the diffs a couple of years ago (I used Mobil 1 LS synthetic in both with 75-140 in back and 75-90 in front) that I noticed that at times I would have a fluid leak out of the vent tube on the front differential. At first I thought it was because the vent tube wasn't angled completely up-slope as it had a dip in it which caused a "sump" area of the hose. But I have noticed a bit of a gear whine in the last two weeks, so I decided to put the vehicle up on the Quickjacks I just got in mid November (a pair of 7000TLX, which are SO SO nice to use) and I pulled the fill plug to find I couldn't feel the fluid level with a finger. I put in just about 3/5 of a quart of 75-90 M1 LS fluid to fill it up so it dribbled out. I put the plug back in place, but have yet to drive it to see if anything was damaged. I am hoping I was just hearing bearing noise and that there was enough still in there to keep it from eating itself.

Now, I did my due diligence and found out there was a TSB about the fluid spillage from the vent and that there was a "diff cover" kit that included a baffle to keep that from happening. Well, considering everything I had going on I did all of this before putting the vehicle up in the air and I found a NOS kit on ebay for $250 shipped. Considering it is a "fix" I let my oldest make the choice and got it ordered since you can't find this "kit" anywhere else. That was before I saw the hell that you have to replace the front diff cover, because as far as I can tell, you need to pull the whole diff to get it in, correct?

Then, since I actually had my focus on the vehicle and the issue and not every other sort of hell going on in life I actually came up with a catch-can solution. Utilizing a oil-blow-by catch can, I figured I would mount it near where the vent is up by the vacuum reservoir, pull the 3/8" NPT plug out of the bottom, put in a hose barb and connect the vent line to that. Then I would cap off the "inlet" orifice at the top of the catch can and put the "vent" on the outlet of the catch can at the top. That would allow fluid to get into the catch can, but it would drain back into the diff when you stopped. I can't imagine it being able to push out more than the catch can capacity (3 ounces) while driving. I mean even if you drove 250+ miles straight (the capacity of the fuel tank) when you stopped for gas it would have to drain back when you stopped to fill up.

I mean, I know the "fix" is the baffled diff cover, and as long as I have that on-hand I can save that for a future date. Again, seem reasonable?

Honestly, if I would have thought of this solution I would have never ordered the diff cover kit. But alas, it is done and will be here Friday. Now, the ONLY reason I figured it was reasonable to order it is because the seller is within an hours drive from me. So if the kit is not as represented (ie, if it has a regular cover, not a baffled cover, for instance) and if eBay won't force him to refund me, I can always just drive to where he lives and have a chat about scamming someone online. I mean $200+$50 shipping is outrageous for this "kit" considering it is a baffled diff cover and possibly a gasket and bolts. So, as long as it is "all good" then so be it, I will have it for when I have more time.

Honestly, the wife has been driving the Explorer more than I have (I have been driving my daughters 2001 Acura TL because I have had to park in hospital parking structures and at doctors offices and I don't care to drive my luxury vehicles or the Explorer to those places) so I didn't even know about the noise from the front diff until I drove it last Thursday to do some shopping with her. I promptly parked it when we came back and this last weekend finally got it in the air.

Again, any and all input on the cooling system and front diff is appreciated, as always.

 

[Pete Deering]

Hey guys, I haven't posted in a while because, quite frankly, everything else in life has gone to hell, but I digress...

In the past two years we have put almost 17k miles on the 42k mile "survivor" 1996 Ford Explorer XLT. As a quick recap we redid just about everything about two years ago. New cooling system (everything but the heater core), new synthetic fluids everywhere (including the diffs), new brakes (hoses, calipers, rotors, pads), new shocks, new front end suspension components, etc, etc...

When I redid the cooling system I used an Autozone radiator, thinking that if I have problems it is a quick swap-out because of the lifetime warranty. Well, wouldn't you know it I ended up having a coolant leak and was trying to figure out exactly where it is coming from. It was leaking on the drivers side front of the engine dripping down the side of the block in the front corner from above. In looking there isn't any bolts that go into the cooling system and the waterpump was brand new 2 years ago (motorcraft) along with everything else. None of the cooling hose clamps were loose and I couldn't see above because of the A/C and power steering brackets. But after a bunch of research I figured it was one of two things, either a freeze plug (highly unlikely as there is virtually no rust on the engine at all, just surface rust with teh age and no rust on the freeze plugs), or it is the intake manifold gaskets (I couldn't believe the design when I saw what Ford used from the factory, literally a paper gasket with a small embossed silicone bead). Given the age and everything else I figured it had to be the intake manifold gasket, but still went investigating.

I noticed the coolant was down in the reservoir and it was above an inch or two down in the radiator, so I filled everything back up and then started it from cold and let it pressurize. Well, wouldn't you know it but before it does I see it squirt coolant out of the passenger side radiator end tank at the seal where the end tank is crimped to the core. That is on the opposite side of the engine bay and couldn't account for the coolant seen on the drivers side.

So, considering I have to replace the radiator I figure I would also do a coolant bypass at the heater core valve. Ever since I did the cooling system a couple of years ago I noticed that if you have the heat on the coolant temp would go way up and then drop way down when the thermostat opened. I used a Motorcraft OEM thermostat and it works properly just that there is no "bypass" hole in the thermostat outside of the ball-valve that allows you to bleed the system properly (which closes under pressure). I also noticed that the coolant hose on the passenger side at the top of the engine gets a bunch of pressure when the temp shoots up and it relieves when the thermostat opens. I am sure that is why the end-tank on the radiator popped a seal and it can't be good for the cooling system as a whole to be quick-cycling like that in winter.

Now, while I was waiting for the radiator (*******s at Autozone made me order a replacement since they no longer carry them in stock, which I will get refunded when I return the bad one), I put on a "known bad" radiator cap that won't hold pressure and noticed no more leaks in the cooling system, either from the radiator end tank seal or the drivers side.

Now, I know the factory "fix" was a coolant bypass that utilized the cooling system temp sensor for the gauge as a bypass point that used a 3/8" line and ran from that point down to the intake hose just before the waterpump. I would gladly utilize the same kit if it was available, but alas, it is not. Piecing together a "kit" also seems like a major PITA considering that I would need to source a tee for the temp sensor as well as a tee for the big hose and all that jazz. Also considering that a 5/8" heater hose seems to do a good job when the heater bypass valve is in bypass mode in the summer I figure the only real issue is a reduced amount of coolant flow through the heater core compared to it being bypassed. So I picked up two 5/8" x 3/8" metal tees ($20 each on amazon) but I had to drill out the inside since they necked down quite a bit on the core of them. I will put on just before the heater core bypass valve and loop the 3/8" sides together and that should give an "escape path" for the extra coolant that is not going to run through heater core (also, as a side note, the heater core is perfect on the inside, I scoped it and there is not corrosion or debris plugging it, it just doesn't flow as well as a 5/8" hose and I get GREAT heat out of it). I figure I will still get plenty of coolant flow through the core in doing this. I will also reverse the hoses at the core to make sure it stays "clear".

Does this seem like a reasonable and valid way of dealing with the bypass issue?

Should I also drill a small hole in the thermostat (or basically just remove the ball "valve" to allow it to mix coolant as well)?

Lastly, Should I also do the intake gasket as well when I do the radiator? Or do I get it all back together with the bypass and thermostat hole and see if the extreme pressure was causing the leak and if it doesn't leak at all I am good? (Hey, I gotta be honest, having time to do the intake manifold is something I really don't have given what is on my plate right now, I mean I am a totally "pro-active" person in taking care of issues, but is there ANY chance it was a pressure based issue and without extreme pressure spikes I will be "OK"?)

Next issue is the fact that after I redid the fluids in the diffs a couple of years ago (I used Mobil 1 LS synthetic in both with 75-140 in back and 75-90 in front) that I noticed that at times I would have a fluid leak out of the vent tube on the front differential. At first I thought it was because the vent tube wasn't angled completely up-slope as it had a dip in it which caused a "sump" area of the hose. But I have noticed a bit of a gear whine in the last two weeks, so I decided to put the vehicle up on the Quickjacks I just got in mid November (a pair of 7000TLX, which are SO SO nice to use) and I pulled the fill plug to find I couldn't feel the fluid level with a finger. I put in just about 3/5 of a quart of 75-90 M1 LS fluid to fill it up so it dribbled out. I put the plug back in place, but have yet to drive it to see if anything was damaged. I am hoping I was just hearing bearing noise and that there was enough still in there to keep it from eating itself.

Now, I did my due diligence and found out there was a TSB about the fluid spillage from the vent and that there was a "diff cover" kit that included a baffle to keep that from happening. Well, considering everything I had going on I did all of this before putting the vehicle up in the air and I found a NOS kit on ebay for $250 shipped. Considering it is a "fix" I let my oldest make the choice and got it ordered since you can't find this "kit" anywhere else. That was before I saw the hell that you have to replace the front diff cover, because as far as I can tell, you need to pull the whole diff to get it in, correct?

Then, since I actually had my focus on the vehicle and the issue and not every other sort of hell going on in life I actually came up with a catch-can solution. Utilizing a oil-blow-by catch can, I figured I would mount it near where the vent is up by the vacuum reservoir, pull the 3/8" NPT plug out of the bottom, put in a hose barb and connect the vent line to that. Then I would cap off the "inlet" orifice at the top of the catch can and put the "vent" on the outlet of the catch can at the top. That would allow fluid to get into the catch can, but it would drain back into the diff when you stopped. I can't imagine it being able to push out more than the catch can capacity (3 ounces) while driving. I mean even if you drove 250+ miles straight (the capacity of the fuel tank) when you stopped for gas it would have to drain back when you stopped to fill up.

I mean, I know the "fix" is the baffled diff cover, and as long as I have that on-hand I can save that for a future date. Again, seem reasonable?

Honestly, if I would have thought of this solution I would have never ordered the diff cover kit. But alas, it is done and will be here Friday. Now, the ONLY reason I figured it was reasonable to order it is because the seller is within an hours drive from me. So if the kit is not as represented (ie, if it has a regular cover, not a baffled cover, for instance) and if eBay won't force him to refund me, I can always just drive to where he lives and have a chat about scamming someone online. I mean $200+$50 shipping is outrageous for this "kit" considering it is a baffled diff cover and possibly a gasket and bolts. So, as long as it is "all good" then so be it, I will have it for when I have more time.

Honestly, the wife has been driving the Explorer more than I have (I have been driving my daughters 2001 Acura TL because I have had to park in hospital parking structures and at doctors offices and I don't care to drive my luxury vehicles or the Explorer to those places) so I didn't even know about the noise from the front diff until I drove it last Thursday to do some shopping with her. I promptly parked it when we came back and this last weekend finally got it in the air.

Again, any and all input on the cooling system and front diff is appreciated, as always.

Response too the following:. Ever since I did the cooling system a couple of years ago I noticed that if you have the heat on the coolant temp would go way up and then drop way down when the thermostat opened.
On my 95 4.0 ohv. Ford has a TSB on that, which is a bypass hose that goes from the lower radiator hose to the port where the coolant temp sensor is located for the temp gauge. It did not really work, so I removed it. The problem is there is air trapped in the upper manifold. The solution is to vacuum bleed the coolant system.

 

[DP96XLT]

Pete, thanks for the reply...

A little background, almost two years ago I did the waterpump, radiator, hoses, thermostat, thermostat housing and everything else, I thought I had an air bubble as well, but I vacuum bled the system 3 times, with the last time holding vacuum for 2 hours, then turning it off and waiting another 2 hours and I had no drop in vacuum in that time. I figured it was all good, filled the system through the vacuum system (when I initially pulled vacuum I go through a process where I then go to fill until coolant goes up through the fill side and starts filling, shut that off and leave the fill side "filled" so that no extra air enters the system).

It still did the "rise" to well above halfway and fall with the heater engaged, with the heater off it only goes to just below halfway, at most, and then drops back but in general stabilizes much quicker.

I will not discredit that I might have some sort of intake manifold gasket issue in regards to coolant, and if that is truly the issue I should see "normalization" of the temps once I replace the intake gaskets. That is first on the list here for tomorrow. I have the big one-piece Apex aluminum manifold gasket with the embedded silicone around the ports so that I won't run into the two sides "shifting" when I put the manifold on. I also picked up the Mahle valve cover/intake gasket kit that has the aluminum valve cover gaskets and thicker intake manifold plenum gaskets with the silicone plenum gasket inserts. I figure that HAS to be better than the silicone embossed cardboard gaskets used by Ford originally. I attached a pic of the gasket at the bottom.

Once I get the intake manifold done (which, BTW, I also notice a "rough idle" when restarting the vehicle when warm, which I hope is a sign of the intake manifold gasket issues as well), I will pull the radiator and swap in the new one and then vacuum bleed and fill the system once more. I will run it like that for a few weeks to see if the massive "swing" and resulting pressure is gone and if so I won't do anything else. If it is not gone I will do the extra set of tee-fittings and put in the 3/8" bypass on the heater bypass hoses before the heater valve.

Just in case no-one else read the other thread, I picked up the "last one anywhere" replacement front diff cover kit and they outline a VERY simple way of pulling the diff down to get at the front cover area. I will be doing that as well when I do the intake manifold gaskets along with the radiator swap.

 

[Exploder321]

Torque the intake manifold bolts, that may stop the leak there.

 

[Exploder321]

You may, likely, have a faulty thermostat, swap that with a Stant Super Stat, I've had good luck with Stant. Boil beforehand to verify it opens at the proper temperature. If it doesn't have the tiny check valve, you can drill a 1/16 or so in the same spot, this will let a small amount of coolant flow and provide heat to the thermostat to open a tad sooner. Engine will still warm up properly.

 

[Pete Deering]

Pete, thanks for the reply...

A little background, almost two years ago I did the waterpump, radiator, hoses, thermostat, thermostat housing and everything else, I thought I had an air bubble as well, but I vacuum bled the system 3 times, with the last time holding vacuum for 2 hours, then turning it off and waiting another 2 hours and I had no drop in vacuum in that time. I figured it was all good, filled the system through the vacuum system (when I initially pulled vacuum I go through a process where I then go to fill until coolant goes up through the fill side and starts filling, shut that off and leave the fill side "filled" so that no extra air enters the system).

It still did the "rise" to well above halfway and fall with the heater engaged, with the heater off it only goes to just below halfway, at most, and then drops back but in general stabilizes much quicker.

I will not discredit that I might have some sort of intake manifold gasket issue in regards to coolant, and if that is truly the issue I should see "normalization" of the temps once I replace the intake gaskets. That is first on the list here for tomorrow. I have the big one-piece Apex aluminum manifold gasket with the embedded silicone around the ports so that I won't run into the two sides "shifting" when I put the manifold on. I also picked up the Mahle valve cover/intake gasket kit that has the aluminum valve cover gaskets and thicker intake manifold plenum gaskets with the silicone plenum gasket inserts. I figure that HAS to be better than the silicone embossed cardboard gaskets used by Ford originally. I attached a pic of the gasket at the bottom.

Once I get the intake manifold done (which, BTW, I also notice a "rough idle" when restarting the vehicle when warm, which I hope is a sign of the intake manifold gasket issues as well), I will pull the radiator and swap in the new one and then vacuum bleed and fill the system once more. I will run it like that for a few weeks to see if the massive "swing" and resulting pressure is gone and if so I won't do anything else. If it is not gone I will do the extra set of tee-fittings and put in the 3/8" bypass on the heater bypass hoses before the heater valve.

Just in case no-one else read the other thread, I picked up the "last one anywhere" replacement front diff cover kit and they outline a VERY simple way of pulling the diff down to get at the front cover area. I will be doing that as well when I do the intake manifold gaskets along with the radiator swap.

View attachment 424975

From my core plug replacement, I have a little air left in the system. I only used my spill proof funnel. I see my needle moves from 1/2 to 1/4. So I will now vacuum bleed the system. My question too you is,,: if you pull a vacuum on the system why does it hold? (I know from experience sometime the vacuum will seal the gasket) And when your system is fill, is there a loss of coolant from the system? Is there white smoke from the exhaust?

 

[DP96XLT]

You may, likely, have a faulty thermostat, swap that with a Stant Super Stat, I've had good luck with Stant. Boil beforehand to verify it opens at the proper temperature. If it doesn't have the tiny check valve, you can drill a 1/16 or so in the same spot, this will let a small amount of coolant flow and provide heat to the thermostat to open a tad sooner. Engine will still warm up properly.

I used a Ford OEM thermostat. I did check it before installing and it does work as intended.

I considered drilling an extra hole in the thermostat or just removing the ball valve which would do the same thing.

 

[DP96XLT]

From my core plug replacement, I have a little air left in the system. I only used my spill proof funnel. I see my needle moves from 1/2 to 1/4. So I will now vacuum bleed the system. My question too you is,,: if you pull a vacuum on the system why does it hold? (I know from experience sometime the vacuum will seal the gasket) And when your system is fill, is there a loss of coolant from the system? Is there white smoke from the exhaust?

After I redid the cooling system almost 2 years ago I did not have any sort of coolant leak.

Only recently has it has a coolant leak from above as well as the end tank seal on the radiator doesn't hold.

Lastly, no white smoke from the exhaust. So I do not suspect a headgasket or cracked head.

 

[DP96XLT]

Torque the intake manifold bolts, that may stop the leak there.

Correct me if I am wrong, but there are lower intake manifold bolts that are inside the valve cover area, correct?

I figure I might as well just replace all the gaskets since the original Ford ones have given many others tons of problems (which I attribute to shoddy manufacture and a lack of proper torque everywhere) and this would make it "problem free" with all the "known" intake issues resolved and taken care of.

If I am not considering this properly, let me know... But I figure making sure it is assembled properly with better gaskets would be a way of being certain it was taken care of.

 

[Exploder321]

Trying to think through this thermostat issue, if there was air in the system at the thermostat, the thermostat wouldn't open normally as the heat transfer from the coolant to the expansion bulb would be impeded, driving up engine temp. It seems unlikely there would be air in the system based on the fill process used. You mentioned that when the heat is on is when this occurs. I'm not familiar with your configuration (I have the 5.0), does the outlet from the heater core return to, or near, the thermostat housing? As you know, the heater core removes heat from the coolant to warm the cabin, is it possible that cooler water is delaying thermostat opening?

 

[Pete Deering]

Trying to think through this thermostat issue, if there was air in the system at the thermostat, the thermostat wouldn't open normally as the heat transfer from the coolant to the expansion bulb would be impeded, driving up engine temp. It seems unlikely there would be air in the system based on the fill process used. You mentioned that when the heat is on is when this occurs. I'm not familiar with your configuration (I have the 5.0), does the outlet from the heater core return to, or near, the thermostat housing? As you know, the heater core removes heat from the coolant to warm the cabin, is it possible that cooler water is delaying thermostat opening?

On my 95 4.0L OHV engine, air gets trap in the upper manifold area by the coolant gage sensor; resulting in a fluctuating coolant temp gauge needle. There is a TSB on this issue. After proper purging the coolant system I get all the air out.