Step-by-Step compression test instructions? (DIY) - PeachParts Mercedes-Benz Forum

300DPETE · #1 10-30-2005, 10:05 AM

1982 300D

I've searched, but can't find a step-by-step pictorial/narrative on running a compression test on a 1981-1985 turbo 300D.

I'm interested in getting/renting a kit to do this, but would like to undestand (a little more) what what I'll be doing.

Anyone got a link?

t walgamuth · #2 10-30-2005, 10:35 AM

just a brain.

first. get an adaptor for the fuel injector holes. second get a compression tester for diesels.

third remove injectors and hard lines and put a rag over the injection pump to catch the fuel.

fourth screw in adaptor attach compression tester and crank the motor over about three or four times. record number from tester and release pressure.

repeat for each cylinder.

replace all removed parts.

values will be for cold or hot compression. make note of whether you are testing cold or hot.

prob take less than an hour.

tom w

funola · #3 10-30-2005, 10:59 AM

Anyone do a compression test from the glow plugs? If an adapter can be made and there's enough room for access, seems to be less intrusive than pulling the injectors.

t walgamuth · #4 10-30-2005, 11:02 AM

but haven't done it that way.

tom w

300DPETE · #5 10-30-2005, 01:27 PM

Quote:

Originally Posted by t walgamuth

just a brain.

first. get an adaptor for the fuel injector holes. second get a compression tester for diesels.

third remove injectors and hard lines and put a rag over the injection pump to catch the fuel.

fourth screw in adaptor attach compression tester and crank the motor over about three or four times. record number from tester and release pressure.

repeat for each cylinder.

replace all removed parts.

values will be for cold or hot compression. make note of whether you are testing cold or hot.

prob take less than an hour.

tom w

Thanks, Tom. Do you recommend a particular testing kit?

J. R. B. · #6 10-30-2005, 02:01 PM

Quote:

Originally Posted by funola

Anyone do a compression test from the glow plugs? If an adapter can be made and there's enough room for access, seems to be less intrusive than pulling the injectors.

I've done it with 5.7 and 6.2 GM diesels. Special adaptors came with our compression guage. Just make sure you buy/use a compression guage for diesels. A gasser guage doesn't register high enough.

whunter · #7 10-30-2005, 02:06 PM

http://www.peachparts.com/shopforum/showthread.php?t=126728&highlight=compression+test

The Tool Rental Program should have instructions for the use of each tool.

t walgamuth · #8 10-30-2005, 04:45 PM

one available from the internet, which i bought for a reasonable price. it has an adapter for 616 617 but not 603.

tom w

300DPETE · #9 10-30-2005, 05:27 PM

Quote:

Originally Posted by t walgamuth

one available from the internet, which i bought for a reasonable price. it has an adapter for 616 617 but not 603.

tom w

Link?

t walgamuth · #10 10-30-2005, 05:44 PM

i am not smart enough to do that.

i just ran a search for it. i think i got it off of ebay with a buy it now price.

tom w

300DPETE · #11 10-30-2005, 07:11 PM

Yeah, I checked on eBay, but it's hard to tell which sets are the good sets, and if there's any that should be stayed away from.

Would say $120 be okay for a set that had the MB injector and glow plug adapters?

Pete.

leathermang · #12 10-30-2005, 07:40 PM

Leakdown Tester and ?'s

the compression or leakdown tests can be done from the glowplug hole or the injector hole.. the FSM has pictures of both... and I have posted them....