Cooling system mystery, still...

[MillerAPF97XLT]

Same old truck, but perhaps a new phenomenon. '97 4.0 SOHC, I just changed the water pump along with updating the thermostat housing to the 2002 unit. Almost two days ago is the last time it was started and driven - my stepdaughter, who is about to start driving it as her daily, took it on a shakedown. It gave her no troubles, and she parked it in the driveway. Today, I went to do a fluids check and noticed the coolant recovery tank almost full to the top. My curiosity piqued, I opened the radiator cap and was greeted by a release of pressure from within. After almost 48 hours, I would have expected no residual pressure in the cooling system. Additionally, the coolant level in the radiator was down about a half gallon. Surely this is not normal, is it? At least the residual pressure should alleviate my fears of a head gasket leak, right? What's going on here? Any/all assistance is greatly appreciated. Thanks in advance - Chris:exp:

 

[lobo411]

Everything was fine before the work was done? If so, I'd double-check the water pump--make sure the hoses are properly connected and not reversed, give the pump pulley a tug to see if the bearings seem OK, spin the pump by hand, etc...

Are you sure you refilled the cooling system completely when you did the work? Did you bleed the cooling system when you refilled it? Could be that you had a massive pocket of air in the system. When I flush mine (drain via the petcock), it usually takes 1.5 gallons to refill...at first. Then I start it up, tons of air bubbles gurgle up, and it usually takes at least 1 gallon to get to a more realistic "full" level. Then I drive it around for a few days, checking the level after each drive cycle, and it usually takes a good 1/2 gallon or more to get to "really full."

Anyway, the thing to do is refill the cooling system, bleed it properly, and then inspect. If there is a bigger problem than just an air bubble, then the coolant has to be going somewhere.

 

[Harpua216]

i happen to agree with the above poster. after installation did you bleed or burp the system? take a clean funnel (a bigger bottom hole is better) put it in the radiator and pour antifreeze in the funnel until its filled a little less than halfway while the engine is running to temp. see if you get some air bubbles in the antifreeze and see if you can squeeze some air out of the radiator hose, carefully if its hot.

this will eliminate that as a suspect. silly question... thermostat went in the same way it came out?.. i have hear stories is all, and there's buildup for sure, though I am sure a ripper through town by your daughter eliminates this mostly.

 

[koda2000]

Did you "burp" the system after refilling with coolant after the W/P install? The SOHC engine is notorious for trapping air in the system when the system is drained and refilled.

Trapped air will cause the engine to overheat and blow scalding hot coolant and air into the overflow tank, filling it and sometimes even blowing the cover off. Try refilling the radiator and draining the excess coolant from the overflow tank. Hopefully the engine didn't get so hot that it blew a head gasket. Go for a drive and keep a careful eye on the temp gauge. If the needle doesn't come up normally (or starts to come up and the goes down) that's a bad sign.

 

[MillerAPF97XLT]

Thanks, lobo and Harpua. No, all was not beer and skittles with the Ex before the 'stat housing swap. The old lower housing was cracked, allowing coolant to escape while running and air to enter on cooldown, rather than pulling coolant back in from the recovery tank. Also, the temp gauge was doing this crazy thing where it swept way up towards the red zone, one time during each drive, then settle down to just below halfway. I replaced the pump while I had the front of the engine as exposed as it was as a preventative measure (didn't trust the 192,x..-mile-old original). On the first drive I took it for after repairs, the gauge did the same thing it had been doing before, but no overheat. As for the residual pressure and excessive coolant in the recovery tank, could I have a bad NEW radiator cap, holding pressure rather than letting the system sip out of the tank as it cools? I will have to look, but I don't remember if I replaced it with a Motorcraft; everything else that went on the truck WAS. Again, thanks for the responses. Any others, please weigh in! - Chris:exp:

 

[MillerAPF97XLT]

Just saw your post, koda. I DID burp the system after repairs, but I'm not certain I did it correctly... I've seen elsewhere on this forum that getting the front of the vehicle up high is the key. I went a step further and got the left front even higher (easy-peasy in the Missouri Ozarks!) and ran it at idle for what seemed like forever. Then, while it was still warm, I took a short drive (maybe 4 miles in all) and the gauge didn't act weird at all. The next day or so, I took a 7-mile drive into town and it did the run-to-the-red thing once, early in the trip, and was fine on the rest of the trip in and on the return leg. Then, today, pressure and low coolant under the radiator cap, over-full in the recovery tank. Going to drive it pretty much the same trip tomorrow morning, and will post results after.

 

[Harpua216]

good luck! you have normal heat and AC functions correct? figured id ask.

 

[koda2000]

Just saw your post, koda. I DID burp the system after repairs, but I'm not certain I did it correctly... I've seen elsewhere on this forum that getting the front of the vehicle up high is the key. I went a step further and got the left front even higher (easy-peasy in the Missouri Ozarks!) and ran it at idle for what seemed like forever. Then, while it was still warm, I took a short drive (maybe 4 miles in all) and the gauge didn't act weird at all. The next day or so, I took a 7-mile drive into town and it did the run-to-the-red thing once, early in the trip, and was fine on the rest of the trip in and on the return leg. Then, today, pressure and low coolant under the radiator cap, over-full in the recovery tank. Going to drive it pretty much the same trip tomorrow morning, and will post results after.

Sounds like you got the trapped air out if you were able to get the needle on the temp gauge to come up to normal and drive it 7 miles. Did you install a new thermostat with the new housing? If you did and you're still seeing the temp spike before it returns to normal (about mid gauge). Honestly I'm thinking head gasket. Hope I'm wrong. Your rad cap should be 16 pound release. I've never encountered a defective one.

 

[MillerAPF97XLT]

Hmm. The daughter now reports a rough running condition and a lack of power/acceleration. My test drive confirms this is the case. However, the temp gauge never rose past halfway. But, the VERY stiff hoses shortly after starting and the bubbling into the coolant recovery tank after shutdown doesn't make me have warm, fuzzy thoughts about the head gaskets. Instead, I find myself wondering which of the head gasket sealing additives would get us through 'til maybe winter, when I can take the time to do a head gasket swap correctly (with the engine OUT). This kinda sucks. BTW, the thermostat and radiator cap are newish, with fewer than 100 miles on them. I still welcome any/all input regarding further diagnosis, sealant brand preference, engine swap choices,... Okay, I really kinda want to keep this engine. This is just frustrating.

 

[lobo411]

It's too late for sealant IME. The kind of performance issues (shuddering) you describe and lots of bubbles in the coolant recovery tank are signs that the leaky gasket is about to blow catastrophically. I'd fix it or sideline it now, before you/your daughter get stranded in some inconvenient location.

Can't speak to the SOHC, but on the OHV head gaskets can be done in 2 days if you're taking your time. No need to pull the engine. Frankly, you'd just be asking for trouble by doing that because an old engine has tons of old fasteners, hoses, fittings, and connections that are ready to crumble the second you touch them.

 

[MillerAPF97XLT]

Thanks again, koda and lobo. From what I've read here, the 4.0 SOHC has to come out to do the head gaskets due to the timing chain for the right head being at the rear of the engine. If I have to pull it, I'm doing the timing set, too, so I won't have to later. If I could afford it, it would get a complete rebuild, but... Still open to alternative trains of thought, if any. Thanks to all for the help so far. - Chris:exp:

 

[koda2000]

Bars Head Gasket Sealant with carbon fiber has very good reviews (Advance Auto Parts around $45). However, if your seeing exhaust bubbles in the overflow tank it will nearly impossible to get the sealant into the leak. I just went through this with a friends truck, and while the Bars helped and the truck is currently driveable, it's still leaking exhaust into the cooling system. I tried removing each spark plug to try to find the leaking cylinder to no avail. If we could have determined which cylinder has the leak, we would have stood a better chance of the sealant working, by running the engine with that plug out and the FI disconnected.

Just changing the head gasket will probably not solve your problem either, because your head(s) are probably warped, which is what caused the head gasket to blow in the first place. My friend is driving his truck for now (locally) and we'll see how long it lasts. He's considering a used or rebuilt engin and I wouldn't install a used SOHC w/out replacing all the timing components. It's a lot of work and money either way. Probably easier to find your daughter another vehicle (and ones that gets better fuel economy).

 

[Flash]

Bars Head Gasket Sealant with carbon fiber has very good reviews (Advance Auto Parts around $45).

And it looks cool too.

 

[MillerAPF97XLT]

Thanks, koda and Flash. Hadn't considered the possibility of warped heads. I'm not out any more money on the truck yet, so I'm probably going to go ahead and pull the engine and evaluate. I have started shopping for parts, though, and am wondering whose timing set to buy, Cloyes or Sealed Power. I see DNJ and Enginetech on RockAuto, too, but I personally don't have any experience with them to base an opinion (or trust) on. Also, once I get the heads off, how much clearance is allowed when checking them for straightness? Additionally, since it seems to make a difference with the timing set, how can I tell whether my engine has a balance shaft or not before tearing it down? I'm trying to give my daughter an idea of what repairs to her truck are going to cost BOTH of us!

 

[koda2000]

I believe all the 4x4's had the balance shaft.

 

[MillerAPF97XLT]

You may be correct, koda. Sealed Power's parts description shows a total of 4 chains in the AWD/4WD "complete" set (no balance shaft or crankshaft gears, from what I see).

 

[SootsMe]

Thanks, lobo and Harpua. No, all was not beer and skittles with the Ex before the 'stat housing swap. The old lower housing was cracked, allowing coolant to escape while running and air to enter on cooldown, rather than pulling coolant back in from the recovery tank. Also, the temp gauge was doing this crazy thing where it swept way up towards the red zone, one time during each drive, then settle down to just below halfway. I replaced the pump while I had the front of the engine as exposed as it was as a preventative measure (didn't trust the 192,x..-mile-old original). On the first drive I took it for after repairs, the gauge did the same thing it had been doing before, but no overheat. As for the residual pressure and excessive coolant in the recovery tank, could I have a bad NEW radiator cap, holding pressure rather than letting the system sip out of the tank as it cools? I will have to look, but I don't remember if I replaced it with a Motorcraft; everything else that went on the truck WAS. Again, thanks for the responses. Any others, please weigh in! - Chris:exp:

My 5.0 had a wad of gunk plugging up the the tank/overflow hose joint, which prevented the overflow from cycling between tank and engine. I don't even know what made me check this, other than my world is really weird...