dies at full operating temp

[Overlord]

Vacuum is a steady 6" Hg - vacuum leak?

Compression #:

1 - 125
2 - 150
3 - 122
4 - 142
5 - 20
6 - 110

I think I did the compression test right:

- Warmed her up to operating temp,
- shut her down
- pulled all plugs
- intalled the compression gauge in spark plug hole
- turned the engine over about ~5-6 seconds
- rinse, lather, repeat

I'm going to do a leak down test. Should I do all 6 cylinders, or just #5?

 

[Overlord]

Leak down test:

100% on #5, heard air leaking into #4, no were else from what I can tell.

I did run out of CO2, so I only tested #5.

According to the leak down tester instructions, air leaking to an adjacent cylinder could indicate the head gasket leak. True or false?

Also, would a vacuum leak cause my symptoms? IE dieing at full operating temp.

 

[PAFJ]

Vacuum is a steady 6" Hg - vacuum leak?

Yes, big leak! I think you're dealing with a couple different issues here. The vacuum leak is most likely the cause of your idling issues. Possible bad intake or carb gasket or cracked intake manifold.

The compression test numbers are all over the place. Ideally you don't want more than 10% difference between each cylinder. Couple things, adjust the valves and do another compression test, then do a wet test by squirting some oil into the cylinders. If the numbers go up during the wet test, you have some bad rings.

 

[PAFJ]

Leak down test:

100% on #5, heard air leaking into #4, no were else from what I can tell.

I did run out of CO2, so I only tested #5.

According to the leak down tester instructions, air leaking to an adjacent cylinder could indicate the head gasket leak. True or false?

Also, would a vacuum leak cause my symptoms? IE dieing at full operating temp.

From my experience (which isn't much), a blown HG would show on the compression test by having two adjacent cylinders showing low numbers i.e. #4 and #5 were both 5 or even 0. I would definitely check the valves first, do another test then go from there.

 

[Overlord]

Yes, big leak! I think you're dealing with a couple different issues here. The vacuum leak is most likely the cause of your idling issues. Possible bad intake or carb gasket or cracked intake manifold.

The compression test numbers are all over the place. Ideally you don't want more than 10% difference between each cylinder. Couple things, adjust the valves and do another compression test, then do a wet test by squirting some oil into the cylinders. If the numbers go up during the wet test, you have some bad rings.

How much oil?

 

[PAFJ]

Not much, about a cap full. Let it sit a bit so the oil has time to run down the sides of the cylinder. Also be sure to do the compression tests w/ the throttle wide open... just in case you didn't know.

Good Luck!

 

[Overlord]

Also be sure to do the compression tests w/ the throttle wide open... just in case you didn't know.

Forgot about that, I'll do that next time.

 

[Overlord]

Completed valve adjustment. Seams as I got rid of the vacuum leak and the idle issues. She does not die at full operating temp. Not sure how as all I did was adjust the valves. I did find out that the vacuum gauge tube was slightly to big, causing a low reading. I found out by squeezing the tube.

Compression check #'s:

Dry: Wet:
1 - 150 150
2 - 145 145
3 - 100 100
4 - 140 140
5 - 80 85
6 - 125 125

I'm not sure. Did I f'up the valve adjustment?