Compression test results

[p5150]

I purchased this 300SD not really knowing what is wrong with it for $400 - not a bad deal at all. COLD compression test came out as follows:

1-300
2-270
3-240
4-260
5-260

What do you think?

[Brian Carlton]

For $400. you got a good deal there.

Four of them are a bit low, #3 being the worst, but it will probably do an acceptable job for you. What's the situation with the blowby? It will be interesting to see how it does in 20°F. weather.......or below.

[p5150]

400 bucks WAS cheap. The body is very straight and has minor rust on the left fender in front of the tire.

The original first aid kit is still installed!

Im wondering how the compression is going to change once the engine warms up. Do you think the car will run well as-is?

[Brian Carlton]

The compression will almost always be higher when warm. But, the test is defined as a cold test at crank speed. If you tested it at idle speed, you would have significantly more compression. So, the engine will probably run just fine.

The only caveat is starting it when cold. Now that you have the compression numbers, PLEASE DO report back, on this thread, with it's cold starting capabilities. It's valuable info to have for an engine with slightly less than desirable compression.

You'll start to get into trouble starting it, for sure. Now, whether this occurs at 25°F. or at 10°F. or somewhere in between these two extremes, is the question.

[sailor15015]

Not that I know much but those numbers seem good for a cold engine from what I've read. Have you done a valve adjustment? Correct me if I'm wrong but that can improve compression numbers if they're maladjusted, right? Or do they have to be really off?

[Brian Carlton]

Originally Posted by sailor15015

Not that I know much but those numbers seem good for a cold engine from what I've read. Have you done a valve adjustment? Correct me if I'm wrong but that can improve compression numbers if they're maladjusted, right? Or do they have to be really off?

300 is a good number. But, there is only one of those.

And, yes, if the valves are really off and are not closing, then the numbers will drop. Or, if the seats are in bad shape and they leak, the numbers will also drop.

I wouldn't worry about the numbers unless the performance of the engine is not what you require.

[t walgamuth]

from the seventies says normal cold is from 300 to 320 i think. minimum i think is 218 or so. if the engine has sat for a while and is kindof dry, just getting it running and with fresh oil may bring them up some.

the valves may need adjusting too as noted above.

sounds promising.

tom w

[Diesel Giant]

I thought that high 300's were closer to normal. However make sure your glow plug system is in good shape and plug in your block heater. Anything to keep the old man starting.

[p5150]

Thanks for the input guys! The guy that sold it to me mentioned that it needed a valve adjustment, but I have yet to do so. I need a new valve cover gasket. Any ideas on good locations to purchase one?

[Brian Carlton]

Originally Posted by p5150

Thanks for the input guys! The guy that sold it to me mentioned that it needed a valve adjustment, but I have yet to do so. I need a new valve cover gasket. Any ideas on good locations to purchase one?

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1JU1236H41QB01EX3X&year=1984&make=MB&model=300-SD-002&category=A&part=Valve+Cover+Gasket

[p5150]

I also need the fuel line for the injectors/return line and some other assorted hoses.

[sailor15015]

All those can be found right here at the "Buy Parts" tab on the top of the screen. The prices are good and the shipping times are excellent. I've rarely had anything take more than two or three days to get here. Plus you're supporting the guy that supports this site.

[Brian Carlton]

Originally Posted by p5150

I also need the fuel line for the injectors/return line and some other assorted hoses.

Go to the top of the page and press the "Fastlane" button.

[lrg]

I second (third?) the endorsement of Fastlane. I recently ordered a valve cover gasket that I found had a slight manufacturing defect so probably wouldn't seal properly. Phil had a new one in my hands in a day, no questions asked.

[kmaysob]

Originally Posted by p5150

I purchased this 300SD not really knowing what is wrong with it for $400 - not a bad deal at all. COLD compression test came out as follows:

1-300
2-270
3-240
4-260
5-260

What do you think?

where is your location? anywhere near az?