Help w/ head gasket, plz!

[AKJDL]

I have a '95 Explorer with 4.0 v6. Found a small head gasket leak about 6-8 months ago, losing coolant - no coolant in oil and nothing leaking into radiator. However, idles rough and definitely not developing normal power.

DUMB question, if only one HG is leaking, is it necessary to replace both gaskets? I can't imagine why that'd be necessary, but the I'm not real smart. I'm a shade tree type mech, basic jobs, how tough is a head gasket?

Thanks in advance for any help!

 

[poker4me007]

Do a thorough check and make sure that's where your leak is coming from...You can do one, but if it were me I'd do both your gona have every thing torn apart anyway...It's a pretty big job, if youv'e never done it before best you have someone help you who has...

You don't say how many miles are on the truck, is it worth doing,does it burn oil ,leak oil, do lifters tick ect... depends on your knowledge of engines..
If the truck is in good shape Id rather try and pick up a good used motor and put it in...JMHO...

 

[96eb96]

Doubt it is a HG, cracked heads are quite common. I believe I had a similar issue. Lots of misfires on one cyl. Plug was cracked too. Temp gauge never stayed still. This may be controversial but K-seal completely fixed it for me. My 96 shows misfire counts, I remember it warming up after installing it and seeing the counter stop dead. Was almost shocking. The other day it could barely get up an overpass, CEL blinking. I even bought a set of new premium plugs b/c one was cracked. Now it feels like a new truck.

1000s of miles, driving in the steepest mountain grades at 4-5k rpm sometimes. Just make sure the coolant is clean. Worst case you flush everything out and repair it. I have peace of mind for the lower intake gaskets too, as well as ratty freeze plugs.

I may have done the repair the right way, but there is rust on the truck and I know it won't be around forever. Not saying it is for very modern engines but it worked for me. You can remove the product too, once the repair is done it is really not needed. It supposedly works by wicking silica and copper into the crack, and it welds shut from the combustion temps. Sometimes you have to run it with the plug out of the cylinder, according to the company, but during the exhaust stroke it should get in. Remember places repair cracked heads, so this isn't such a crazy idea.

 

[koda2000]

K-Seal is very good stuff for small leaks and it won't hurt anything. I've had excellent permanent results with K-Seal on the infamous 5.0L timing cover gasket leaks. Give it a try. Worst thing that can happen is you'll be out around $12-$15 (depending on where you buy it).

 

[AKJDL]

Thanks for the replies!

The truck has right at 120k and otherwise runs well. Smooth above 900 rpm...

Wouldn't K seal likely plug the heater core? That's what I'd been previously told, anyway.

This truck doesn't show any temperature changes, although after some hard miles it does occasionally flash a check engine light that is very intermittent.

Otherwise a very solid relatively low mileage truck. It does leak a small amount but of oil, doesn't appear to burn any at all. It's down about a half quart at oil chg - every 3000 miles... No engagement no tappet noises, plugs all looked good and all worn evenly.

 

[lobo411]

My guess: you have a leaking lower intake manifold gasket. This gasket seals two water ports, so you can lose coolant externally when it starts to go. It also affects the engine's ability to develop vacuum, and a vacuum leak can cause a rough/surging idle. They seem to die around 100-150k, so I would direct my investigation in that direction.

They tend to leak at the red area (front and back) in this pic. This is where the water jackets are located:

http://www.explorerforum.com/forums/index.php?attachments/ts-pic-jpg.33984/

But in answer to your question: you should replace both head gaskets at the same time if you decide to do it. Once you've stripped the engine down enough to be able to replace one side's gasket, you only need to do 20 or 30 mins more work to replace the other gasket. It would be foolish not to do them both.

 

[AKJDL]

Thanks!

 

[koda2000]

Thanks for the replies!

The truck has right at 120k and otherwise runs well. Smooth above 900 rpm...

Wouldn't K seal likely plug the heater core? That's what I'd been previously told, anyway.

This truck doesn't show any temperature changes, although after some hard miles it does occasionally flash a check engine light that is very intermittent.

Otherwise a very solid relatively low mileage truck. It does leak a small amount but of oil, doesn't appear to burn any at all. It's down about a half quart at oil chg - every 3000 miles... No engagement no tappet noises, plugs all looked good and all worn evenly.

K-Seal will not clog your heater core, like some products might. It is considered a permanent repair and remains active in your coolant to stop future leaks. It all comes out when you flush your cooling system. I recommend you remove a little coolant from the radiator (8 ounces) and after shaking the bottle very well poor K-Seal directly into the radiator and idle the engine for 20-30 mins.

 

[J_C]

I might try a sealant as a stop-gap (lol, pun intended) measure but just to buy time to do a teardown in spring, taking the approach that it might be head gasket or head crack but if you can't locate it with certainty ahead of time then you just start tearing it down and looking for the source as you do.

I'd buy the head gasket and intake manfold gasket sets, leaving the head gasket set packaged so it can be returned if unneeded. If you find an intake manifold leak, stop there and only put that gasket set on. If there is no leak then take the head off and see if a leak is found. If it's leaking out the gasket them check for head warpage. If it's not then check for head cracks. If neither are found, put it all back together with all new gaskets and new head bolts.

I would do both head gaskets while at it if it gets down to that, and all of the above instead of only relying on a sealant *forever* because it only has 120K mi. Oh wait, you're in Alaska. Might depend on amount of rust then, what the projected remaining lifespan is.

 

[96eb96]

Thanks for the replies!

The truck has right at 120k and otherwise runs well. Smooth above 900 rpm...

Wouldn't K seal likely plug the heater core? That's what I'd been previously told, anyway.

This truck doesn't show any temperature changes, although after some hard miles it does occasionally flash a check engine light that is very intermittent.

Otherwise a very solid relatively low mileage truck. It does leak a small amount but of oil, doesn't appear to burn any at all. It's down about a half quart at oil chg - every 3000 miles... No engagement no tappet noises, plugs all looked good and all worn evenly.

My heat is nice and hot.
Also, coolant must be very clean, no rust, maybe 2yrs old max. I don't know why it clogs in some cases and not in others. One reason could be that it don't seal properly and air is drawn into the system, that could cause it to clog. Also, it may not be used as directed, people may add 3 bottles. Some engines call for sealant, and it is put in the factory to repair any minor casting flaws. Coolant contains silicates too.

When the repair starts to reach the cost of the vehicle, those products may be worth considering.

 

[Terkins]

I have a '95 Explorer with 4.0 v6. Found a small head gasket leak about 6-8 months ago, losing coolant - no coolant in oil and nothing leaking into radiator. However, idles rough and definitely not developing normal power.

Similar problem: Losing coolant (where?) with miles-driven; maybe ~12 oz./320 miles. Same as above: no coolant in oil; no leaks on pavement. New radiator cap. Flushed coolant 2 mos. ago and became suspicious having to add a little coolant here-and-there. Idles fine. Only owned 3 mos./new plugs/wires/136k. Seems to lack power for a 6 cylinder but I've never known what it should do?

4.0L V6 SMPI OHV 12V FEDERAL 160HP; engine order code 99X.

I'm facing becoming vehicle-less if I can't repair it myself. Any good guides to replacing intake manifold gaskets? I'm having it "tested" by a local shop that is thorough--perhaps too thorough--next Tuesday. I barely exist on Social Security/shared roof/food/utilities. I have to do repairs by the side-of-the-road; landlord doesn't allow driveway repairs. I'm hoping it's something like the water pump or something simpler than the intake gaskets...

 

[lobo411]

12 oz in 300 miles is a lot, and I would guess that if your engine was sucking down that much water it would perform poorly. More likely to be an external leak.

Check the hoses. I've had decent leaks from the upper radiator hose to water outlet mating and from the heater hoses at the heater valve.

Check the block where the lower intake manifold gaskets seal the water jackets.

Check the front timing cover generally.

Check the water pump weep hole and gasket.

Check the thermostat housing.

Check the small black hose that runs from the coolant reservoir tank to the radiator. I've had this hose turn hard and start to "sweat" coolant.

 

[Terkins]

12 oz in 300 miles is a lot, and I would guess that if your engine was sucking down that much water it would perform poorly. More likely to be an external leak.

Thanks for the insight/suggestions!

Meanwhile, at Amazon, I discovered this item: , the Mityvac MV4560 Radiator/Cooling System and Pressure Test Kit; $47.00. Seems it would be a handy tool to have around and to help find the leak?

The outdoor temps should return to "normal" next week--~45 deg. F. afternoons--and I can check the sites you listed. Too cold to do roadside mechanic's work for the moment!

If nothing seems evident, I might buy this pressure testing kit and/or some UV dye.

 

[Mbrooks420]

The OHV isn’t a powerhouse by any stretch. You can’t ever smell coolant? I’m assuming you mean head gaskets and not intake gaskets. How many times have you added coolant? Where do you add it?

 

[koda2000]

Agreed that the OHV 4.0 is not very powerful, especially when push 4,000 pound of brick-shaped truck around.

Question: Does your cooling system draw coolant from the reserve tank? Do you find it doesn't and when you remove the radiator cap is the coolant low? If it doesn't draw from the reserve tank you have a leak somewhere and the radiator is sucking air rather than drawing coolant. It might be your radiator.

There's a plastic pan under the radiator, which is held on with 4 10mm bolts. Not sure of its purpose (protection. air deflector?) I've found that this pan can hide radiator leaks because it catches the antifreeze and then will not let it hit the ground in your driveway unless the angle is right. The coolant is blow out while your driving and unnoticed. The most common place for the radiators to leak is from the plastic side tank gaskets.

Remove the plastic pan and look for green staining in the bottom of the pan and alone the bottom of the radiator. If you see any stains (or wetness) you'll need a new radiator.

The 4.0 OHV engine is notorious for developing cranked heads. It could also be you have a cracked head and that coolant is getting into a cylinder. When you changed your spark plugs, was there one that was very white (rather than the usual tan color)? if so, coolant is probably getting into that cylinder. The coolant "steam cleans" the spark plug white.

Question: After running the engine, when you loosen the radiator cap to the first notch does it burp air into the reserve tank? If so, that's a sure sign that you have a cracked head or blown head gasket.

 

[96eb96]

I had a freeze plug leak too, thought it was the lower intake gasket. Tiny leak, and one day I probed it with a screwdriver and it really started to stream. The cracked head business could go on for 10s of thousands of miles before it gets bad. There was even a TSB about steam in these engines, and a special bypass tube. One symptom is a temp gauge that swims around(not necessarily hot). Maybe that was a coverup for the cracked heads. I think the K-seal I talked about above is a good idea, because it is giving you peace of mind for other coolant leaks. Some engines even specify sealant products to address various issues (Northstar for example). If your truck is pristine it may be worth to do heads and gaskets.

 

[koda2000]

I had a freeze plug leak too, thought it was the lower intake gasket. Tiny leak, and one day I probed it with a screwdriver and it really started to stream. The cracked head business could go on for 10s of thousands of miles before it gets bad. There was even a TSB about steam in these engines, and a special bypass tube. One symptom is a temp gauge that swims around(not necessarily hot). Maybe that was a coverup for the cracked heads. I think the K-seal I talked about above is a good idea, because it is giving you peace of mind for other coolant leaks.

I've had excellent results with K-Seal for drip type leaks (and have recommended it), but not for things like cracked heads or blown head gaskets where exhaust is getting pushed into the cooling system. It also hasn't worked for me on side-tank gasket radiator leaks. No harm in trying K-Seal, but it might not work.

 

[96eb96]

I've had excellent results with K-Seal for drip type leaks (and have recommended it), but not for things like cracked heads or blown head gaskets where exhaust is getting pushed into the cooling system. It also hasn't worked for me on side-tank gasket radiator leaks. No harm in trying K-Seal, but it might not work.

The K-seal guy told me to run the engine without the plug out for 15 min. That forces it into the crack. I consider what I have a permanent repair. I also had a cracked plug, ended up replacing all of them with the TT iridiums, had lots of discounts from advance so I used it. Starts in two rotations in 0 degrees.

 

[koda2000]

The K-seal guy told me to run the engine without the plug out for 15 min. That forces it into the crack. I consider what I have a permanent repair. I also had a cracked plug, ended up replacing all of them with the TT iridiums, had lots of discounts from advance so I used it. Starts in two rotations in 0 degrees.

Yeah, I recently tried this on a neighbors SOHC and we could not determine which plug to pull. As radiator pressure is maybe 16 PSI at best and cylinder compression is 160-180 PSI the pressure is no contest.

 

[Morley]

Similar problem: Losing coolant (where?) with miles-driven; maybe ~12 oz./320 miles. Same as above: no coolant in oil; no leaks on pavement. New radiator cap. Flushed coolant 2 mos. ago and became suspicious having to add a little coolant here-and-there. Idles fine. Only owned 3 mos./new plugs/wires/136k. Seems to lack power for a 6 cylinder but I've never known what it should do?

4.0L V6 SMPI OHV 12V FEDERAL 160HP; engine order code 99X.

I'm facing becoming vehicle-less if I can't repair it myself. Any good guides to replacing intake manifold gaskets? I'm having it "tested" by a local shop that is thorough--perhaps too thorough--next Tuesday. I barely exist on Social Security/shared roof/food/utilities. I have to do repairs by the side-of-the-road; landlord doesn't allow driveway repairs. I'm hoping it's something like the water pump or something simpler than the intake gaskets...

Intake gaskets are not hard to do, nor do they take a lot of time