Cylinder Head leaks/Coolant Questions - with pictures! | Ford Explorer Forums - Serious Explorations

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Cylinder Head leaks/Coolant Questions - with pictures!

Dash Riprock

Active Member
Joined
April 9, 2005
Messages
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City, State
LA, CA
Year, Model & Trim Level
95 Explorer XLT
Hi all, please forgive the long post. I am currently dealing with a coolant leak/cylinder head gasket problem and Ive got a few questions beyond the usual "where is my coolant going" offerings.
Some background: '95 XLT, 160K, 4.0 OHV. This is my wife's car which I never paid much attention to (Im busy, damnit). When I started to, I found the coolant low, and the temp guage never rising much above "C". Odd, I thought. Seems like the two are in opposition to each other. Anyway, I found and fixed a leaking heater control valve, then replaced a stuck open or bypassing thermostat (lots of corrosion), and threw on a new radiator cap for good measure. I thought I had it beat.

And then away went my coolant again. I climbed underneath and found the leak. See the 1st pic. This is forward looking aft, from the right front corner of the car, up at the passenger side engine block. The leak is apparent at the middle exhaust port underneath the manifold. What is amazing to me is the same condition exists on the drivers side, in the same place.

IMG_1679.jpg


So, I have simultaneous, driver and pass. side leaking CH gaskets. This from a engine that was running abnormally low temps and to my knowledge had never been overheated. No record of pinging, knocking, loss of power all the time this was occuring. In fact, it seems the faulty thermostat may have saved the engine.

My question is, well, wtf? How do both gaskets blow? What would cause this other than overheating. Is it possible to overheat with low coolant all the while the temp guage never showing any movement?

After searching this forum and reading many threads I came away with a few tests I could do. The first thing was I pulled spark plugs (autolite platinums). See pic below, do these look like a coolant in the cylinder situation? I didnt think they did, but Im no expert. The insulators are whitish-tannish with one showing some pink tinges. (The coolant is green) The electrodes do have a whitish-light greyish powder, but they arent encrusted. Both plugs are dry.

IMG_1678.jpg

IMG_1676.jpg


Next I tried the cold start with radiator cap off trick to see if the cooling system was being pressurized by compression. Upon starting I got no gusher, no bubbles, no squirts. The coolant did begin to slowly rise though within 10 seconds of the engine start. Is this normal? By ~20 seconds I had to shut down or the coolant would have started seeping over the filler neck. I revved the engine as well.

I was not able to perform a compression test. By the indications on these simple tests, It seems that I have a externally leaking only, blown head gasket. It does not appear to be going to the cylinder. No white smoke, no exhaust smell. Last weeks oil change showed no milkiness. Oil level is not rising artificially. The problem is, how can cooling system pressure alone blow a gasket, correction, TWO gaskets!? Is there some way to overpressurize it that the rad. cap wouldnt vent?

Finally, I have one last very important question. How long can I survive like this and how long can I go before it has to be fixed for real. I need this thing to last through a long camping trip and I dont have time now to dive into it, if I decide to do that at all. Ive seen mentioned many times this "Bars Leaks" stuff and bought some last night. I have not used it yet. Will this help or hurt, does anyone have any experience with it? The only way I can descibe the severity of the leak is to note that it consumes one overfill/catch tank full every week of normal work driving (10 hours) . And each time it is empty, removing the rad. cap reveals the coolant full up to the neck.

Thanks for reading this novel. I appreciate your replies and advice. I just put a reman'd tranny in this a year ago too, and am now torn between selling it and losing that investment in the trans, not to mention the huge project of fixing the CH gaskets.
 



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Those plugs look ok to me. I'm thinking you just have a leak, as you suggest, and it's not likely to get worse by huge degrees. I can tell you I lived with a similar leak at the intake manifold on my 4.0 Explorer for quite some time before fixing it.
 






I take it your temp gauge is working now that the engine has coolant? That should pretty well answer the coolant questions. Like Glacier said it probably is stable now so try the Bars. So now you will fill the expansion tank every time you fill the gas tank but it works and monitoring will tell the rest.
 






Thanks Glacier, I was hoping someone would say that. I wont sue you if it goes all "Old Faithful" on me in the middle of the Sierras... ;)


Papa, yea the temp gage ran right up to mid range. My wife was very happy that the heat suddenly worked... I wish I had known.

Another side affect is that between the engine running at correct temp, conversion to Amsoil, and cleaning the crusty throttle body, ive bumped the mileage on this thing from mid 16s to the high 19s-mid 20s mpg.


I guess what stumps me is why did both sides leak. If the coolant got so low that the truck was overheating, the gauge should have shown it. I mean the cooling system wasnt empty. And clearly the guage is working.

I worry that there is still oil getting in the system, and from reading this forum I know there is a test that can determine this. I will probably get the test so I know what I have to do.

Thanks for your replies
 






the plugs look fine to me.

Really the only way to know for sure is by tearing it apart, rinse, repeat.

Try cleaning up there really good, get all the gunk outta the way. Im thinking you might be able to slab a little JB weld up there or something to stop it, maybe.

My other thought was the lower intake manifold gasket. But im not to familiar with that issue to tell you for sure. If the lower inake loosened up (mildly common) it is known to show leaks around the exhaust manifolds. But what kills this idea is the fact its in the middle of the engine, i dont see how the lower intake can be correlated.

I say clean it, and run it like it is. See if you can pinpoint where it is comming from. If its too much of a byotch to clean, a little grey paint wont hurt.
 






You might try retorqing the head bolts to slow down the leak and to help ensure the leaks don't get worse. That may or may not help.
 






A couple thoughts:
When I first bought my 91 Navajo, the temperature never went above the C. After replacing the thermostat during routine maintenance the temperature went into the midrange. A couple months ago I got a new thermostat from the dealer and the temperature never rises above the C again. I'm guessing that the stock thermostat has a lower temperature than the one you get aftermarket.
Also, when you run the car, the water heats up and expands. That would explain why the water comes out the radiator opening. With the cap on, the system becomes pressurized.

I had same problem with disappearing water at the same rate as yours. I couldn't see an external leak though. No white exhaust. I had one drop of oil in my coolant when I drained it. At any rate, last week I changed the heads (cracked intake to exhaust on the same cylinder) and the gaskets and no more problem. The hardest part is removal of the exhaust manifold. PB Blaster worked better for me than liquid wrench. Remove the wheel well covers to gain access to the bolts (10mm). I knocked the exhaust to y-pipe flange askew causing an exhaust leak that required 2 more rusted bolts to be removed and reassembled.
Hope this helps.
 






If you are going to re-torque the head bolts first you might want to insure that they are not the type of head bolts that you turn an additional 80 degrees after they are tightened to the specified torque. If they are, as are the head bolts that are in my 1993 Ford Explorer 4.0, then I would not recommend tightening them. These bolts literally stretch as they are turned the additional 80 degrees. Should you attempt to torque them again you may run into unexpected or poor results such as snapping a head bolt.
 






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