Valve tappet adjustment

[Little Jo]

Hi All

I am seeking advice from MLU members who have adjusted the tappets on a 1942 MB Willys Jeep. I did a compression test and had readings for the numbers 1- 2 and 3 cylinders showing between 100 lb and 105 lb, however the number 4 cylinder was down to 75 lb. the spark plugs showed no oil but were black as if running too rich.

I decided to adjust the tappets, particularly on number 4. I have never done this before and as a novice I consulted my manual which shows a photograph on how to do it. I aslo consulted G503 on the internet which showed how to do it step by step. The photos and narrative also show removal of the mudguard.

Is it possible to effectively adjust the tappets without having to remove the mudguard, this is not mentioned in my manual, so before tackling the job I thought it a good idea to obtain some expert advice from someone who has done it before. Hope you can help.

cheers

Tony

[Mike Kelly]

Tony

From memory, it isn't the easiest job. I would remove the guard .

MIKE

[Bob Moseley (RIP)]

Hey Tony - I thought we had been through this. You need to know if it is valves or rings so do the oil test as I suggested. It is pointless adjusting the valves if it is a ring problem.

Bob

[Mike Kelly]

Originally Posted by Bob Moseley

Hey Tony - I thought we had been through this. You need to know if it is valves or rings so do the oil test as I suggested. It is pointless adjusting the valves if it is a ring problem.

Bob

Tony

Have you squirted some oil down the cylinder .. then re-done the comp. test ?

If it has a broken ring , stuck ring or worn rings etc.... then , after the oil squirt , the compression will come up , it seals the rings to some degree .

If the compression doesn't change , then you most likely have a leaky valve seat .

But before pulling the head off, do the valve tappet adjustment , it might be just a tappet nut come loose holding the valve open ?

MIKE

[Phil Waterman]

Tony- While checking the valve adjustment is probably a good step anyway. Have you done or thought about a leak down test using compressed air?

This is one of my standard diagnostic test prior to start tearing things apart. It is done by introducing compressed air through the spark plug adapter for your compression gauge. Each cylinder is tested at or near top dead center for that cylinder, with vehicle in gear brake on this is so the engine doesn't try to turn over. I generally set the pressure regulator at 50 PSI apply the pressure.

Listen for-

• sound of air leaking in adjacent cylinders - blown gasket possible
• sound of air leaking from carburetor - leaking intake valve
• sound of air leaking from exhaust- leaking exhaust valve
• sound of air from oil filler or crankcase breather- bad rings

You may need to vary the air pressure but if you have a real problem it will be very noticeable.

When you check the valve clearance take note of those that have decreased and if any of them have gone to "0" of course that indicates real valve wear.

[Little Jo]

Hi Mike - Bob - Phil

Some good ideas suggested there, thanks for the heads up, That has given me some further diagnostic checks to make before I start stripping down. It is always good to hear from others who have tackled the job first hand.

Cheers

Tony

[Little Jo]

Originally Posted by Mike Kelly

Tony

From memory, it isn't the easiest job. I would remove the guard .

MIKE

HI Mike and Phil

I have completed all tests again as per your suggestions. I found that the compression reading on number four cylinder still showed a reading of 75 lb and did not change after adding 5 ml of oil for the wet test. Mike. I also removed the mudguard and as you suggested and it certainly makes it easier too work on.

I recruited my wife Jo to assist with the cranking job and was pleasantly surprised when she accepted as she has not really shown much interest in the restoration project, her standard comment was, "Boy's and their toy's" I am sure she was surprised that I actually completed the restoration.

Cheers

Tony

[Mike Kelly]

Tony

5ml of oil isn't much.. maybe not enough !

If the tappets on that weak cylinder are OK, then you probably have a leaky valve .

Try Phils idea , use an old spark plug and braze a compressor fitting on to it ...or a tight fitting clamp might do.

After you pump the air into the cyl. put your ear next to the exhaust outlet and listen for a hissing sound . Then go to the carby and listen.


Or just go for it pull the head off !

Mike

[Little Jo]

Originally Posted by Mike Kelly

Tony

5ml of oil isn't much.. maybe not enough !

If the tappets on that weak cylinder are OK, then you probably have a leaky valve .

Try Phils idea , use an old spark plug and braze a compressor fitting on to it ...or a tight fitting clamp might do.

After you pump the air into the cyl. put your ear next to the exhaust outlet and listen for a hissing sound . Then go to the carby and listen.


Or just go for it pull the head off !

Mike

Mike

Thanks mate, I will do the wet test again with more oil and have a look at the other suggestions as well.

Cheers

Tony