Possible blown HG and smog test? (1 Viewer)

[joe1520]

Hey all - you got a mudder Noob here!

I just had a compression check done on my '85 60 with a 2F and got back the below results. What are the odds that this is a blown HG vs valves/rings? In reading through older posts, I have a feeling it's most likely the HG, due to the cylinders affected (2 & 3), but open to input. If HG, how much damaging would it be if I continue to drive it (while i put together funds to fix). Not planning on any long dist trips anytime soon.

Also, I'm due to get her smogged (in CA) and wondering what this means for passing? Exhaust is clear, engine is running at normal temp, and have a newly rebuilt carb (rest of emission sys relatively new as well).

 

[ntdb]

You can test your HG using a "combustion leak detector". It pulls air from your radiator through test fluid and the fluid changes color if there are exhaust fumes in your coolant system. I loaned one from O'Reilly last week to check my engine since I've been losing coolant and seeing white smoke on startup.

 

[OSS]

Give it a complete tune-up before (every) smog test.
Then test it.
Pass or fail you need to take the cylinder head off eventually to find out what's wrong.
Whenever the cylinder head comes off (after this many miles) it should be taken to a machine shop to inspect. Most likely most of the exhaust valves aren't sealing tight - which will give low compression. Also the valve stem seals definitely need to be replaced.
Yes it's ok to drive it around town with uneven compression if coolant isn't getting in the oil.

My Plan of Action:
1. Tune up
2. Smog test, pass or fail
3. Remove cylinder head when you've got the time and money to deal with it. It does take some time and it's not a small job due to all the smog equipment that has to be removed and replaced and kept track of.

The headgasket will naturally get replaced when doing the head.

I've removed/replaced a 2F head in a FJ60 six times in my life (not all on my vehicle). It's always a lot of work.

 

[MoaByte]

I believe I have the same problem. Oil and coolant are clean but 2 adjoining cylinders have lower compression. Could be exhaust valves, anyhow I'm getting blue puffs from the exhaust when shifting. Vacuum gauge has a flicker. 118,000 miles.

 

[2mbb]

How is your truck running? What do the two numbers associated with each cylinder represent? Do you know how the mechanic did the test (were all the spark plugs removed for the all the tests, was the engine cold or warm, etc.). I agree with OSS about the tune up, and the tune up should include a valve adjustment. Then do the smog test and see what happens.

Also can you clarify about your emissions system being relative new? as far as I know most of these parts have been long discontinued...

Below is a table for compression tests on my '85 2F (I haven't done one in a while!). All tests were done with the engine warm, all spark plugs removed and the throttle wide open. I generally crank the engine through 5 or 6 compression cycles until the reading seems to max out. I don't have any worries that my head gasket is blown.

Good Luck.

 

[joe1520]

Give it a complete tune-up before (every) smog test.
Then test it.
Pass or fail you need to take the cylinder head off eventually to find out what's wrong.
Whenever the cylinder head comes off (after this many miles) it should be taken to a machine shop to inspect. Most likely most of the exhaust valves aren't sealing tight - which will give low compression. Also the valve stem seals definitely need to be replaced.
Yes it's ok to drive it around town with uneven compression if coolant isn't getting in the oil.

My Plan of Action:
1. Tune up
2. Smog test, pass or fail
3. Remove cylinder head when you've got the time and money to deal with it. It does take some time and it's not a small job due to all the smog equipment that has to be removed and replaced and kept track of.

The headgasket will naturally get replaced when doing the head.

I've removed/replaced a 2F head in a FJ60 six times in my life (not all on my vehicle). It's always a lot of work.

Thanks OSS - sounds like a solid plan.

How is your truck running? What do the two numbers associated with each cylinder represent? Do you know how the mechanic did the test (were all the spark plugs removed for the all the tests, was the engine cold or warm, etc.). I agree with OSS about the tune up, and the tune up should include a valve adjustment. Then do the smog test and see what happens.

Also can you clarify about your emissions system being relative new? as far as I know most of these parts have been long discontinued...

Below is a table for compression tests on my '85 2F (I haven't done one in a while!). All tests were done with the engine warm, all spark plugs removed and the throttle wide open. I generally crank the engine through 5 or 6 compression cycles until the reading seems to max out. I don't have any worries that my head gasket is blown.


View attachment 2617303

Good Luck.

Overall running pretty strong, though i do have a ticking noise that sounds like it could be a loose valve.

Not sure about those numbers either, i was more focused on the pressure figures. Will ask and report back (unless someone knows). All plugs were removed and test was done warm.

I just meant it has new vacuum hoses/connections and cat, in addition to the aisan rebuild.

Seeing your figures gives me a bit more peace of mind that this may be valve related, esp considering the exhaust is clean.

Will get that tune up and have the valves adjusted. Fingers crossed!

Thanks for the help guys!

 

[Spike Strip]

I really don't see anything wrong with your Compression #s other than just a tired motor. But as stated, a good test would be to check for Combustion gases in the coolant. Those kits are cheap, or, again, you can borrow/rent from Auto Parts house.

The valve adj may bring your numbers up, some.

Have you put a vacuum gauge on it to see what that number is?