Once again i'm getting mixed answers on this issue.

Here are the symptoms......

1. Starts up with a slight miss.
2. Runs with miss at idle and higher RPMS.
3. Hardly wants to idle though.
4. Once it warms up...it hardly runs at 200 RPM.
5. White/Blue smoke from around exhaust manifold and tailpipe.
6. NO SIGNS OF MOISTURE IN OIL PAN!!
7. Plugs are dry at end. Threads on plug show moisture.....but only on 4,5 and 6.

Any suggestions folks??

One person told me that the cats were stopped up.
Another says head gasket.

Yet another at a garage says neither. That it's simpler......but he wanted me to drag it into his shop for diagnosis (@ $93 an hour).

 

Ok what have you done so far?
an
Compression? With all plugs out, variances more than 10 - 15 PSI can indicate a problem with ring or valve seating. You are looking for much larger differnce like 50 - 80 lbs or a big fat 0 reading

Do you have any over pressurization in the cool system? Any boiling bubbles or over heating? If so it could be a cracked head up to a blown gasket. CO2 leak detector would eliminate the possiblity of cracked castings.

Not all blown gaskets or water leaks/cracks will show in the oil and visa versa.

Now as far as far as the Cats being stopped up, Install a vaccum gauge to a direct sourse of intake vaccum, start he engine and @ an idle observe the gauge. It should read 18 -20. Stomp on the gas and let the accelerator snap back quickly the gauge should go to zero and recover back to the 18 - 20 almost immediatly. If it hangs on the low side and recovers slow then there is a restriction somewhere in the exhaust system.

IMO with what you have presented and not knowing if you are overheating. My bet would be a blown gasket.

If you are calling the right bank 1,3,5,7 and the left bank 2,4,6,8, I don't understand how 5 is wet. 4 and 6 are adjacent cylinders so that makes sense.

Did you overheat @ one point? If so you might have damaged/warp one head more than another. Of course this is speculation on my part.

I'm going to refer you this post # 5 for the block tester.

Dave

 

Its a straight 6 xj40.

Gonna do compression check a lil later.

Wonder what the compression should be (cold,hot) on a 3.6?

No bubbles that I could see.

 

The AJ6 engines can ocasionally blow headgaskets, it is a known problem, but not hugely common. Normal blow is between two adjacent cylinders. Best not to leave too long as combusion burning can erode the block deck thus needing block skimming, (a hard job), as well as head, (relatively simple). Both block and head are aluminium, hence you need to be cautious.

 

Not so much what it should be is that its even within 10% of each other. That is a good rule of thumb. Actual numbers anywhere from 125 - 175 depending on Comp ratio. Good strong battery, stroke the piston the same number of times, and open the throttle plate.

I just noticed you posted hot or cold. Perform cold. If you have a lot of variances you can add a bit of oil and see if the compression goes up in the cylinders that are low. I dont mean 0 either. Variances in the 10% rule say one cylinder is 90 LBS while the rest are 125 you might wanna look @ this cylinder for ring/cylinder wear hence a few drops of oil. Anything that is drastic especial adjacent cylinders that have equally low pressure is a good indication of a bad gasket.

LOL I should have looked where you had this posted I would have know it was a straight 6. Fraser is right don't wait to long to fix it. If the block or head erode past the fire ring in the head gasket it's going to be big money as well as a complete tear down to deck the block and head.

BTW I starting giving you a bum steer with this comment in the first post. "With all plugs out, variances more than 10 - 15 PSI indicate a problem". That is a somewhat a correct statement for a used motor that you may be looking to install as a replacement, but not for the trouble shooting your are doing.

I hate typing I have to re-read so many times to make sure I said what I meant.



Good luck!

 

OK......did compression check.

Real weird here folks...

cyl 1- 105
2-100
3-100
4-105
5-100
6-100

WTF????

 

Here are the results from wet test.

1-105
2-120
3-110
4-130
5-110
6-120

Head gasket???

 

Those numbers seem a bit low all around. When I did mine with 100k miles or so it was in that range but my compression tester did give me some very erratic readings at times for some reason. Getting compression up to 200 psi in a cyl with a burned valve for example. It was chaulked up to a worn out tester. So when you feel like your readings are funny ensure you have a good tool.

Your dry test has readings that seem on the low side (haynes says 150-160 psi on a warm engine 300k rpm0) but are all in the same range. The wet test shows some variances that might start to indicate worn rings especially on number 4.

Here is Haynes wording:
7: Crank the engine at least seven compression strokes and wathc the guage. The compression should build up quickly in a healthy enigne. Low compression on the first stroke followed by gradually increasing pressure on succesive strokes, indicates worn piston rings. A low compressiion reading on first stroke, which dosent build up during successive strokes indicates leaking valves or blown head gasket etc.

9. Add three squirts of engine oil to each hole.

10. If the compression increases after the oil is added, the piston rings are definately worn. If compression dosen't increase significantly leakage is occuring at valves or cyclinder head.

12. If one cylinder is 20% lower than the others, and the engine has slightly rough idle a worn exhaust lobe on camshaft may be cause.

14. If compression is way down or varies greatly perform a leak down test by an auto repair shop. (Do this. Did mine myself but this will tell you exactly whats wrong.)

Here is what AllDataDIY has:
NOTE :The cranking speed must not drop below 300 rpm and the throttle must be wide open.Compression Pressure 200-220 psiDifferential between cylinders 10 psi (max)

I did not pay attention to my max variation on account of 'Hey it runs...' when I did mine. I'll have to look back at old threads to recall my compression findings. I did have one up to 200 psi might have been when I was wide open? I never pressed throtte conciously and ended up with readings somewhere in range of Haynes.

Like you I had interesting readings and opted for a leakdown test. Pressurise with a air compressor and guage each cylinder and listen and feel for leaks and see how well the cylinder holds pressure. I ultimately found my problem was a burned valve for sure when I had the car running and unpluged spark plugs individually and found that one cylinder did not affect the running quality when unpluged as much as the others did. Hearing air rush down the exhaust manifold and feeling it come out the tail pipes confirmed the valve condition.

Ensure your compression readings are proper and see. Right now your numbers seem low but the dry test yield uniform results. Wet test yeilds increases over ten percent on a number of cylinders especially #4 and 20% on 6 and 2. This is good indication of worn rings from what I have been reading but the all around low readings seem to indicate something else might be awry. 100 psi is as you have found about the threshold for what a car engine can run on.

Do a leakdown test.

 

I agree with gunnerman. Your number are way to low even for an engine running an 8:1 comp ratio. Do a leak down.

 

Havent done a leak down yet.

Will soon.

What else could it be in compression is TOO low?

 

Rings, Valves, or Head gasket bout it.

 

I do have a feeling that it's time to lift that head !

 

lol

leak down I would here it thru the oil filler right??

 

If it's rings yes to the oil filler. if it's intake valve intake manifold and so on. Now if you hear it coming out of the adjacent cylinder, guess what........... what for it .... ah you got it already... yup .. head gasket.

Make sure you take all the plugs out at the same time just for that reason plus it make it a lot easier to turn over by hand.