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-   -   Engine Compression/Worn Ring Question: 1984 300TD (http://www.peachparts.com/shopforum/showthread.php?t=214927)

aaronkobi 02-27-2008 12:39 PM
Engine Compression/Worn Ring Question: 1984 300TD
 
I have a couple questions, and yes, I did search the forum first ;)

My compression tested at 275psi and was consistant across all cylinders. My mechanic said this wasn't bad, but not great. Said the rings are probably worn.

First of all, is 275 a fairly average compression for a 300TD with 175k miles? If I was to correct this in the future, would it require a complete rebuild, or could I just have the cylinders bored and new rings installed? Has anybody had this done, and if so, what was the ballpark cost?

Thanks, this forum has been a lifesaver.

kerry 02-27-2008 12:48 PM
I wouldn't do anything with compression at 275 apart from driving it. It's a little low, particularly at that mileage and might cause some starting difficulty in cold weather. To overcome this, I'd just plug in a block heater. This assumes that a valve adjustment has been done.

mobetta 02-27-2008 12:50 PM
as long as it is close across the board, I dont think that is too bad.
how are the cold starts?
oil consumption?
wvo/svo use in the plans?
last valve adjustment was???

I am pretty sure you can get oversized pistons/rings, but a piston set is a lot of $$$$. another route is to re- sleeve the engine, if your pistons are good. sleeves are cheeper than pistons. but if it were me, as long as cold starts and oil consumption were acceptable, I'd drive it.

aaronkobi 02-27-2008 01:14 PM
Thanks guys. This makes me feel better.

Just had a valve adjustment AFTER compression test. Cold starts with a single crank now at 30 degrees. Below that, it WILL start, but, takes a few tries. With the block heater plugged in, starts on the first crank, every time.

Oil consumption is minimal (drove 1000 miles from florida to DC without a noticable drop in level). No WVO plans, but I am currently running B20 and would like to run B100 in the warmer months.

GRIESL 02-27-2008 01:39 PM
Quote:
Originally Posted by aaronkobi (Post 1776295)
I have a couple questions, and yes, I did search the forum first ;)

My compression tested at 275psi and was consistant across all cylinders. My mechanic said this wasn't bad, but not great. Said the rings are probably worn.

First of all, is 275 a fairly average compression for a 300TD with 175k miles? If I was to correct this in the future, would it require a complete rebuild, or could I just have the cylinders bored and new rings installed? Has anybody had this done, and if so, what was the ballpark cost?

Thanks, this forum has been a lifesaver.
Was your test done hot or cold? Cold that number would be great. Warm, and that's a little low. I think around 435 warm is like new condition.

aaronkobi 02-27-2008 01:48 PM
I'm assuming the test was done warm. The testing and valve work was done by Don Poole in Arlington, VA. Great shop, good guys.

toomany MBZ 02-27-2008 02:15 PM
What is your compression now?

RAYMOND485 02-27-2008 02:15 PM
Engine
 
1984 300d Turbo 146k
New Engine At 144k From Mercedesengines.net 1-800-622-6867, And Do
The Trans Same Time Save $400.00


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