One cylinder 260psi - PeachParts Mercedes-Benz Forum

Blackbolt · #1 03-05-2013, 12:46 PM

I found a federal om617 locally for a descent price and the seller posted the results of his COLD engine compression test all cylinders test at 300psi except number 5cyl tests at 260psi. The engine is from an 85 w123 with 200k miles and includes all acc. including the turbo. I really don't want to pass on the chance to pick up a federal engine but the low pressure cylinder is a huge red flag. Buy or pass?

pawoSD · #2 03-05-2013, 12:50 PM

Could be an improperly adjusted valve causing the low compression.

eatont9999 · #3 03-05-2013, 12:58 PM

Quote:

Originally Posted by pawoSD

Could be an improperly adjusted valve causing the low compression.

I agree. Unless he did a valve adjustment before the compression test, those results are worthless. On top of that, I believe a true compression test is done on a warm engine.

Adjust the valves to spec.
Run engine up to temp.
Pull injectors.
Test compression.

t walgamuth · #4 03-05-2013, 01:16 PM

The low cylinder does not make a useless engine but it should be reflected in the purchase price.

Blackbolt · #5 03-05-2013, 01:51 PM

Considering I can get any om617 at pick n pull for $250. How much would a federal with odd compression go for? I'm thinking $350 since it has all accessories. Btw he is asking $800! Lol!

vstech · #6 03-05-2013, 01:58 PM

I'm assuming the engine is not in the car any longer... how are you to know the mileage?

pull the valve cover and look at the bananna rails. if there are grooves in them, pass... over 400K on them, or POOR oil change intervals...

pawoSD · #7 03-05-2013, 02:06 PM

Quote:

Originally Posted by Blackbolt

Considering I can get any om617 at pick n pull for $250. How much would a federal with odd compression go for? I'm thinking $350 since it has all accessories. Btw he is asking $800! Lol!

We picked up a practically mint 617 turbo minus the alternator/starter/P/S pump for $550 with only 160k on it about 3 years ago. Perfect compression.

Blackbolt · #8 03-05-2013, 02:32 PM

Quote:

Originally Posted by vstech

I'm assuming the engine is not in the car any longer... how are you to know the mileage?

pull the valve cover and look at the bananna rails. if there are grooves in them, pass... over 400K on them, or POOR oil change intervals...

That's right, it is not in the car and the CL posting doesn't claim an exact mileage. Just that it was "around 200k". I suppose 300k could be considered "around" lol! Thanks for the tip! I'll be sure to check for grooves when I check out the rest of the engine.

eatont9999 · #9 03-05-2013, 02:49 PM

That's a lot of money for an OM617 that has not recently been rebuilt. I only paid $850 for my car and I got all the accessories, too. I haven't check the compression but the main reason I bought the car is because it started on a 90% dead battery. To me that says it has pretty good compression.

wildhorsemfg · #10 03-05-2013, 02:51 PM

blow by would tell you if around 100k , 200k , 300k ,
but if you cant run it they can claim anything ....

i have 2 pull and save stores close by and neither of them ever have any diesel engines

Blackbolt · #11 03-05-2013, 03:43 PM

Quote:

Originally Posted by wildhorsemfg

i have 2 pull and save stores close by and neither of them ever have any diesel engines

The lucky thing about living in the pacific northwest is that hipsters love these cars so there are plenty around my location. The yard closest to me has x4 w123's. Although, whether those still have engines and acc is not for sure.

t walgamuth · #12 03-05-2013, 03:57 PM

Quote:

Originally Posted by Blackbolt

Considering I can get any om617 at pick n pull for $250. How much would a federal with odd compression go for? I'm thinking $350 since it has all accessories. Btw he is asking $800! Lol!

I'd wanna be around the 350 range or find a better engine.

barry12345 · #13 03-05-2013, 05:18 PM

In todays world you just do not buy an engine that is out of a car. Unless it is from a member on this site that is very crediable or someone else that is.

There is just too much work involved to find out later that the engine had issues. Eight hundred is also too much for the situation you describe. Best to find another car complete. This gives you a chance to check out the engine properly before even buying the car . Remove what you want from the car and sell the remains to a wrecker if the engine is good.

Our members have enough accidents that one of their smashed cars may be a good source as well. The problem with engines is the distance away sometimes.

barry12345 · #14 03-05-2013, 05:21 PM

Quote:

Originally Posted by vstech

I'm assuming the engine is not in the car any longer... how are you to know the mileage?

pull the valve cover and look at the bananna rails. if there are grooves in them, pass... over 400K on them, or POOR oil change intervals...

Even then the milage is usually suspect but the general condition of the car at least can indicate what the reality might be. We are lucky in the northern rust belt as rust is a direct cause of cars going to the salvage yards or being cheap to buy with decent mechanicals still present.

pawoSD · #15 03-06-2013, 10:34 AM

Quote:

Originally Posted by barry12345

In todays world you just do not buy an engine that is out of a car. Unless it is from a member on this site that is very crediable or someone else that is.

There is just too much work involved to find out later that the engine had issues. Eight hundred is also too much for the situation you describe. Best to find another car complete. This gives you a chance to check out the engine properly before even buying the car . Remove what you want from the car and sell the remains to a wrecker if the engine is good.

Our members have enough accidents that one of their smashed cars may be a good source as well. The problem with engines is the distance away sometimes.

I bought my OM601 on the sellers word, (car it came from was around, but it had been pulled). Turned out fine....I cranked it sitting on the floor in my garage at home for the first time it had run in 2 years (did an oil change first) and it fired right up once it got fuel. It now lives in my W201 and has covered over 1,700 miles so far. I did replace the injector nozzles and delivery valve seals...but thats it!