Author Topic: 200psi = low compression? (Read 6533 times)

sprstu · « **on:** December 04, 2006, 07:13:07 pm »

I just bought my first volks diesel, 1980 caddy, from a guy in new mexico. from his mouth, it runs fine, but with lots of smoke at start up but it will clean up after warmup. the engine tested at 200psi, which is a little low. The car has lived all of its life at 5000ft elivation, which could have something to do with the low compression.

what is normal compression, given the engine is 26 years old?

I will be bringing this car up to Minnesota, so it will not be be living at a very high elevation at all, but it is really cold here now. I am worried a bit about the compression because of the weather, and fear that I will have a very hard time getting it to run. Any thoughts?

Kudagra · « **Reply #1 on:** December 04, 2006, 07:18:02 pm »

I believe a diesel engine needs 350psi or about 15bar to ignite the diesel fuel. So 200 would not be good. Unless its a Petrol engine. Then 200 is great.

vwmike · « **Reply #2 on:** December 04, 2006, 07:30:18 pm »

I would question those results as I don't think it would run with compression that low. The lower limit is 398 psi. A healthy engine should make around 450 psi.

burn_your_money · « **Reply #3 on:** December 04, 2006, 08:58:35 pm »

I'd also agree that the engine shouldn't be running at 200psi. There are alot of factors that need to be considered when checking compression and perhaps one of more were neglected. I'd get the compression rechecked. If you are using the injector ports make sure to get new heat shields

anarchyx34 · « **Reply #4 on:** December 04, 2006, 09:32:08 pm »

200psi is a typical gas engine CR. That cant be right.

sprstu · « **Reply #5 on:** December 05, 2006, 08:46:39 pm »

an engine running at half of its regular compression should not run at all, so the fact that it runs at all means that he messed something up during the test.

jtanguay · « **Reply #6 on:** December 06, 2006, 01:18:04 am »

you would be surprised... i've seen a toyota diesel run on 2 cyls... smoke like crazy but once it was warmed up, it was like the other 2 cyls came to life... lol crazy... but you could tell the motor had no balls... and blowby... holy crazy blowby!

i would definitely be boring/honing/installing new pistons & rings if i were you. guaranteed to last about 300'000km anyways, and be easy to start up in the cold

it actually sounds like something is sticking... which would make sense since you run the compression test when the motor is cold. either rings or a valve...? lifters?

sprstu · « **Reply #7 on:** December 07, 2006, 09:50:41 pm »

i dont have the caddy yet, still need to go and get it. should be a cool/dangerous journey. its 1400 miles away and all. I plan on replacing it with a 1.6td block anyway. now that I think about it, it probably wouldnt be more money to have it bored and replace the pistons and rings and just run that block for my turbo set-up...

burn_your_money · « **Reply #8 on:** December 08, 2006, 04:17:51 am »

with oil squirters of course

Baxter · « **Reply #9 on:** December 09, 2006, 04:04:00 pm »

check and set the valve clearances and re-test!
1980 will be on bucket and shims, and they never get checked/adjusted when they should.

sprstu · « **Reply #10 on:** December 10, 2006, 09:03:11 pm »

what are bucket and shims?

Author Topic: 200psi = low compression? (Read 6533 times)

anarchyx34

Baxter