When testing the compression of an 850 Turbo...is 120 on all cylinders bad?

 

Ooooh. Good question. I was wondering the exact same thing.

 

https://volvoforums.com/forum/volvo-850-16/volvo-850-96-t-5-blue-smoke-%40-idle-29993/#post160434

between 120-150

 

I saw somewhere its supposed to be like 158 to 186 or something like that. I was very alarmed when I read it but not sure if it was correct.

I have had a bad oil leaking problem that I have been trying to tackle. I was thinking after I saw that that maybe my problem was blow-by. Too much in the crank case.

 

Oh, I'm planning on doing a compression test this weekend, be interesting to see what kind of shape this engine is in. So what happened with that blown engine of yours? You fix it now or something?

 

I am exploring all options. I dont have much time to spend on it so I have been looking to replace the engine and at the same time pulling the head to see if it can be repaired. I am at the timing belt and thats my last item before I pull the head. So I can still turn the engine over and will do the oil test. I found a V70 engine at the wrecker but turns out it wont work for me...but, there is a 16T turbo on it...I may snag it.
Let me know what your compression is please, it will help me understand more.

 

Will do

 

I have a 94 850 turbo, with what I hope is a burnt valve. It has over 300,000 mi on it, and my compression test result was as follows.

1. 160
2. 160
3. 160
4. 0
5. 150

I hope this helps give you an idea on the range, I think I saw on Vadis it was in the 160 - 180 range? don't remember though.

 

This may be kind of a dumb question, but what does the compression test all tell you? Like what does it mean if you have good compression and bad compression?

Thanks.

 

well if you are 0 on one cyl its prolly a valve... doubt that its rings, you would KNOW then.

good compression vs bad compression...

well if you have good compression and even compression. sweet your good to go.

if you are week on some cylinders (fluctuating). its prolly bad rings, and or bad valve seats. (being an older car you can expect for the compression to be a little low, but not a WHOLE lot.

if 2+ cylinders are very low (below 85) its prolly a head gasket.

if 1 cylinder is low, or dead its most likly a valve, unless you are spewing out oil from the tail pipe, then its a broken ring.

 

I feel good about my compression for a 300,000.+mi engine. Tech has already put me on the burnt valve.

 

I am expecting a blown head gasket on mine. I had 120, 120, 120, 120, 60. Helps you target it.

But, here is the bad news for me....Tonight I tried the Oil squirt test. First tested the compression in #1 ...was 120 then a squirt of oil in the chamber and tested again....180. Oh boy, that does not sound good.

 

4 out of 5 cylinders.... thats more than 50%... actually... consider it a gas saver and make it a 4 cylinder engine, just unplug the injector for the bad cylinder...

 

that sounds like rings dude....

 

Yankkkkker out!!!

 

Aaarrrrgggghh!!

 

I cant recall specs, but for some reason i think its like 160-175 maybe?

 

Ohh ok. It will be interesting to see what mine turns out to be, I don't really have any reason to suspect that there would be poor compression on any of the cylinders.

 

Please post when you get the results...Real comparisons are very welcome.