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Intake gasket leak is a known failure on the 4.2 V6.
Some say it is only 97-98s but I have a 2002 that had a bad internal intake gasket leak. It was really obvious though, it blew a steady cloud of white smoke which is actually steam.
If you look at the 4.2 intake gasket you can see that the coolant crossover passage is directly adjacent to the intake tract and separated from leakage only by that O-ring type gasket. The isolator bolts holding the intake on have a weird grommet that can fail, the bolt effectively "loosens" and then gasket leaks. I'm not saying that is for sure what your problem is but it is a known issue. It isn't really that bad to change them. Make sure all surfaces are really clean before putting it back together.
Thanks Sam, but I'm not sure if I understand... Are you referring to that rectangular port next to the #3 cylinder?
Also, I'm trying to understand if/how that would affect the compression readings... It's on the other side of the valves, right? ...I don't understand... That's why I was thinking head gasket instead of intake gasket.
I heard about that intake gasket as a known issue, but I looked up the production date and I think mine was built after they addressed the issue. Also, the milage on mine is way higher than the stories I heard about it.
In any case... I probably need that intake gasket too, since I've had foam under the oil filler cap for over a year now. But if I go that far into it, I'm thinking I should do the head gaskets too. I'm just trying to understand it better, before I begin anything.
here's a couple pics of the oil filler cap and dipstick;
Before you pull the head and intake you need to determine IF there is a problem.. How much antifreeze are you using ? Does the level drop in a week / month/ year ? Do you have compression gas inside the radiator ? ........... some foam on the fill cap is normal. How far do you drive each day ? Length of trip ?
Before you pull the head and intake you need to determine IF there is a problem.. How much antifreeze are you using ? Does the level drop in a week / month/ year ? Do you have compression gas inside the radiator ? ........... some foam on the fill cap is normal. How far do you drive each day ? Length of trip ?
Thanks again Steve. I agree about making sure before starting the job.. I guess it would be about $500 worth of parts and machining to do the head gaskets, and I'd be pissed if that didn't solve the problem!
About the radiator; it seems to be holding water pretty good right now. A couple weeks ago I had to fix a leak in the lower coolant hose, and the level has stayed good since then.
I don't know how to check for compression gas inside the radiator..
I've been running straight water in the radiator ever since I first noticed that foam on the filler cap. ...I heard that anti-freeze is very hard on the crank bearings if it gets into the oil...
My usual drive is usually only about 20-30 miles per day. That would include about 10 minutes worth of highway speeds, and then a lot of back streets and boulevards. There's usually a bit of a hill somewhere along the way too. Sometimes the hills are fairly steep too (but usually nothing like the one I mentioned in this thread).
On a side note, when that lower coolant hose sprung a leak, the engine was pinging pretty loud at mid-throttle (on the highway), but when I stepped on the gas, it went away. Also, the temp gage was still in the good zone. It was a little on the high side, but it wasn't too hot. None of the lights came on either... No CEL, no temp light, nothing... The oil pressure gage jumped around a little as I was pulling off to a safe spot to stop, but that's. it.
You would think that 30 minutes of driving would warm things up so all condensation was gone, but could depend on the humidity....... If you NOT using antifreeze, then I would not try to "fix" something by pulling the head or intake.. 20 miles a day is 100 miles a week... If the coolant level does not change in 2-3 weeks, I don't see a leak problem ......... so the "foam" would be condensation. ......... and you don't need to do a radiator combustible gas test if your not using coolant.
Thanks again to all you guys who responded... I have a little update, but I still don't know what's going on.
For starters, the Check Engine light went off by itself!
...I cleared the codes two or three times, and coming down that particular hill always set it off again. When I get to flatter ground, it always stoped flashing, but it stayed lit.
A couple days ago, when I went to start it, the battery was a little weak but she did fire up. Then I noticed that the CEL was off. That seemed strange since I hadn't cleared the codes lately.
I haven't been back to that same hill since then, so I don't know what will happen when I do go back up there...
The only things that are different since then:
1- I found a place that sells "ethanol free" gas. It's 89 octane instead of the usual 87 that I use.. I don't see how that could make a difference, but it seems like it's worth mentioning.
2- Back when I checked the compression, the #2 spark plug wasn't as tight as the others... I don't think it was actually backing out of the hole, but it wasn't as tight as I expected it to be either. In any case, I did the compression test with ALL the plugs out, and even though #2 was the low one, I don't see how that would matter either.
Last night, I did a little math to convert the compression numbers that I got...
As mentioned earlier, someone said that 175-180 psi seems really high. [The numbers should've been around 135.]
So, assuming that the gage I was using is off by 25%, I converted all the numbers.
12-20-2017, 07:54 PM
