98 Exp 4.0 OHV Coolant Loss/leak, Misfire, Cylinder Head Advice

[Dono]

The symptom I had with my cracked head was this:
Any time I stepped on the gas for 15-30 seconds, I'd develop a miss in #3. I'd pull #3, and the porcelin would be cracked.

Im certain that when I would step on the gas, the motor would suck coolant in to cyl #3, and destroy my spark plug.

Im guessing that a bad head gasket could cause the same issue.

 

[Betsy98Sport]

I guess if I have another bad head gasket, that wont be so bad and worth fixing. I only hate to have to take it apart again. I dont want to do this annually. That means I have to get new head bolts and another head gasket. I still need to do the compression test even though Im almost certain this is another head gasket.

I think I'll go with another brand this time if that's the problem. I thought the Fel-Pro was pretty good. I got the higher end product last year.

 

[Dono]

I used the Fel-pro high end, and I don't (Think?) I have an issue. Although, I am pulling Cyl #3 misfire codes right now. I just ordered a new injector. I think I'll abandon my truck if its a head issue.

 

[Betsy98Sport]

Compression Test Results

These are the results of the compression test for each cylinder in PSI:
1 - 167, 166
2 - 165, 165
3 - 164, 166
4 - 143, 145, 147, 147
5 - 166, 167
6 - 156, 157, 157, 158

I measured 4 and 6 four times because I wanted to confirm that they were lower.

So they all fall within spec according to Haynes.

The only thing that has shown anything is the pressure test which showed a slight leak somewhere. Unfortunately there was no external leak that was visible.

Currently my Ex only has rough starts occasionally that last for less than a minute and then its runs great. Some starts aren't rough at all.

I noticed that once the humidity went down since fall weather is here, its gotten better. The coolant reservoir still slowly goes down over time.

Any thoughts?

 

[Dono]

Ya, your pulling some coolant in to your motor, either thru your head gasket, or a hairline crack in a head. Maybe lower intake gasket again?

But which is it? Whick bank?? Im still no further ahead on my misfire issue either.

No spark plug issues?

 

[Betsy98Sport]

Ya, your pulling some coolant in to your motor, either thru your head gasket, or a hairline crack in a head. Maybe lower intake gasket again?

But which is it? Whick bank?? Im still no further ahead on my misfire issue either.

No spark plug issues?

I'd hope it was just a gasket. Lower intake preferably. Taking those heads off is a pain. The spark plugs looked good. The misfire was shown to be in cylinder 3 so the compression test does not match. Head gasket seems to be unlikely

 

[Dono]

Bank 3 seems to be where it all happens.
At the back lower intake usually blows out. The factory cylinder heads are weak on Cyl 3 on one bank(Back of motor) and Cyl 4 on the other bank.

Its interesting that my #3 is whats misfiring also.

It seems that some of these issues are almost impossible to diagnose.
On coolant loss, You almost need to just tear the top end apart, starting with lower intake and see if you can see the gasket seeping. If you pull a head, do you replace it for the $300.00?? Its painful to keep replacing parts. Even though I replaced my heads, I am having issues also.

 

[Betsy98Sport]

Bank 3 seems to be where it all happens.
At the back lower intake usually blows out. The factory cylinder heads are weak on Cyl 3 on one bank(Back of motor) and Cyl 4 on the other bank.

Its interesting that my #3 is whats misfiring also.

It seems that some of these issues are almost impossible to diagnose.
On coolant loss, You almost need to just tear the top end apart, starting with lower intake and see if you can see the gasket seeping. If you pull a head, do you replace it for the $300.00?? Its painful to keep replacing parts. Even though I replaced my heads, I am having issues also.

I got my heads last fall and they were redesigned with reinforcments in the spots where they crack and twist. I wouldn't waste my money replacing them. I don't think that's the issue anyway.

 

[Dono]

Well, we both seem to be in pretty much the same boat.
My #3 cylinder compression is quite low also (80 to a max of 120). I'm going to see about having someone with a leak down tester see if they can give me more info.

Your compression numbers are way higher than mine, interestingly enough. My best cylinders numbers are 1st stroke 100, 3rd stroke 150

 

[Betsy98Sport]

The engine is continuing to pull in coolant with no outside leak. I've done a coolant pressure test, compression test. Not sure what else I can do.

It is noticably worse with the misfires. I do notice it more often when the car is first started, under load (up hill), sat for a long period of time, or if its humid outside.

What should I do now?

Also does anyone have advice on doing the compression test. I usually let the engine turn over 6 times and take a measurement. I know that squirting oil in will determine whether its a piston ring issue but the compression is so good before that I didn't bother looking.

And