Low Compression Repair Procedure????

[Thomas M]

Say a compression check shows unacceptable, low cylinder pressures............

How is the repair accomplished?????

Can the head be checked out for leaks, warpage, etc. if it is pulled and out of the car???

What about the block and cylinders??? Can they be honed, etc. and new pistons, rings fitted if still in the car???
Does the engine have to be pulled??

Is it worth doing any other head work at that time if mileage is the main concern???

Big mystery for someone who is a neophyte when it comes to these repairs.

[82vdub]

Quantum man has talked about doing a plastic bottle hone to his engines over the years. I believe it was Hagar that talked about the procedure for honing the cylinders with the engine still in the block, and I think the pistons still in the holes. If I remember, he pushed the pistons down, filled the cylinder with parafin wax, honed the cylinder, then cleaned it out. The wax sealed the top of the piston and kept the shavings from going down into the ring grove area.

If the head is warped or shot, it should be rebuilt. Are you sure the valves are closing properly by checking the shims? What if you open the cylinder and find that it's worn beyond salvage. Do you pull it apart and redo it all, or just hone the cylinder and put it back together and hope for the best??

I'm sure the pistons can be pulled with everything still in the car, but it would be some work to hone the cylinders without getting debris all over the bottom of the engine with it still in the car. Reassembly would be challenging as you'd be working from the top and bottom of the car, but it would be workable.

[Thomas M]

If it comes to pulling the engine then, what else would you rebuild after almost 300,000 miles???

Certainly clutch and related components.

What about the tranny??? I do get a little crunch when going into 2nd gear once in a while.

The injection pump and injectors rebuilt, front seals.....all new recently.

Just pulling things out of the air here.

I mean if it has to be major surgery, I might consider going all the way.
I've had this car for 23 years and don't intend(???) to buy another unless someone slams into me.

Then, again, if the cylinders check out ok, it will just be the head work, I guess.....have to wait and see.
Just some planning ahead here.

I'm going to check the compression and maybe do a leak-down test. That will help my decision.

[82vdub]

It really depends on what's wrong with the car and your budget. You can rebuild the trans to eliminate the 2nd gear crunch, or wait another 100k miles and do it then, or ?? If the engine is out, a clutch is cheap to replace while it's apart. For the engine, if you pull and disassemble, what needs to be done will need to be determined by you or your machine shop. If it can get by with a hone on the cylinders, then you can probably reuse the pistons, if they check out ok. But, the engine and it's condition needs to tell you what all you need to replace, in addition to the commonly replaced parts during a rebuild (rings, bearings, gaskets, etc).

[Thomas M]

The compression check will tell a lot. The shop got 400, 400, 360, 460(1 through4) a few weeks ago. They said the low one could just be carbon and advised to drive it and check again later.....which I intend to do myself.

I'm also doing a mileage and oil consumption test. It doesn't seem to be leaking gas into the cooling system.......
If you recall, I overheated and blew the heater core...it ran fine right after that, even without any repairs. No smoke, easy start, good idle......it just got hot if driven too far.
Now, with new cooling system and front seals, new IP and injectors it's running well.

I'll get back with the test results...........................thanks.

[Quantum-man]

Hi,
A little late with my advice , but then again, you've not updated:
Re 'carbon causing the low compression' I don't see how , unless they mean a ring is sticking in.

Most likely ring gaps aligned. Otherwise, your compression levels are high enough for satisfactory operation.

Funny coincidence:My engine with the 'Plastic Bottle Hone' has just had an alignment issue. Now corrected!