Low/0 compression

[tonio]

I recently bought an early A-4 to replace my even earlier one. This new motor had low to 0 compression on the #s 1, 3 and 4 cylinders and the valves were way out of adjustment. The #2 was fine. There were a few sticky valves which loosened up easily. The head, pistons and cylinders looked in decent condition. I put the head back on but still had very little compression on those 3 cylinders. Might there be there some trick I could try to cure this so I don't have to pull the pan and bring the cylinder body to a machine shop?

I drove a long way to get this motor, and I still want to end up with a good deal.

Thanks allot,

Tony

[tonio]

Ater searching the site further I found Dave Doolin's reply about using brake cleaner sprayed into the cylinders through the spark plug holes and replentishing it so that it sits for several days.

Would turning the motor over by hand, or with an air wrench help in any way?

I have drained the oil from the motor. should I replace it before trying this?

Thanks for all of the great information,

Tony

[redwitch]

I belive the engine sat for a while, 3 of the cylinders had a open valve, one cylindre had closed valves, the cylinders with closed valed has compression, rust may be the prolbem.

[tonio]

Thank you Redwitch,
did you mean rust on the valves, so that they aren't seating? They all looked in similar condition to the valves for cylinder #2 with no rust, but some carbon. I just looked at them and brushed them off some, and am not sure if looking is an adequate method of determining whether they will seat or not.

Thanks again,

Tony

[Don Moyer]

Tony,

I spoke to a gentleman who had successfully used a brake cleaning product to restore compression and asked him to post his procedure on the Forum for others to benefit. It's my understanding that the process is most useful in cases where valves and rings are partially bound by carbon or by caramelized goo (typically caused by a partial restriction within the exhaust system).

Turning the engine over a few times after adding the bake cleaner would probably help, but I'm not sure that you would have to drain the oil before using the brake cleaner. I'd recommending changing the oil afterward, and adding Marvel Mystery Oil to the fuel.

Regards,

Don

[tonio]

Thank you Don,

I went ahead and poured a bunch of solvent into the cylinders and worked the crank shaft back and forth quite a bit. Compression came up on the #s 3 and 4 but the #1 which had 0 compression before remained that way. I have filled that cylinder again and am letting it sit, although I am just about resigned to taking the motor apart and brining the cylinder body to a local machine shop to have them change the rings and check out the overall wear.

I did want to afirm what you said about the problem occurring when the exhaust had been obstructed. It was the exhaust valves that were way out of adjustment and stuck, and when I drained the oil, the last of it was as thick and cruddy as I had ever seen. We have a farm and I take care of our equipment, so I have seen a bit of oil.

Thanks again for the information and great site. I will be ordering your manual
when I get the chance,

Tony