Compression tested my junkyard OM606

Compression tested my junkyard OM606 - Printable Version

+- STD (https://www.superturbodiesel.com/std)
+-- Forum: Tuning (https://www.superturbodiesel.com/std/forumdisplay.php?fid=6)
+--- Forum: Engine (https://www.superturbodiesel.com/std/forumdisplay.php?fid=7)
+--- Thread: Compression tested my junkyard OM606 (/showthread.php?tid=8085)

Compression tested my junkyard OM606 - Granfatherglock - 07-14-2018

I posted this in my build thread, but I figured I'd copy it here as well since it's more relevant.

Finally got around to compresion testing my boneyard om606. It didn't go well.

Ended up breaking cylinders 5 and 6 glow plugs. I attempted to extract both without success. So I decided to compresion test 1-4. If they're good I'll keep it and get the machine shop to extract those two glow plugs. If' not I'll bring her back to the scrapyard and keep looking for a good donor.

Well here are my test numbers using the glow plug holes, a spare battery connected to the starter, a battery charger set to 50A on the battery, and a screwdriver to jump the starter. It turned over sooo slow, so I hope that has something to do with the terrible compression numbers. I did not add oil or anything, just screwed my adapter in to the glow plug hole and turned it over.

#1-200psi
#2-220psi
#3-200psi
#4-150psi

I really hate to call this thing toasted, because they're somewhat difficult to get here in the US. This one was dirt cheap, About $300 for the engine and trans. I figure including purchase price, I can rebuild top and bottom end and still not go over $1.5k which is what I'd expect to pay for a wrecked 98-99 w210, or importing a good used engine. I don't have a leak down tester that will fit my glow plug adapter, but I may have to rig something up or at least pull the oil pan and valve cover to see if this thing is even worth salvaging.

Any thoughts, recommendations?

[Image: ESF8xGWh.jpg]

RE: Compression tested my junkyard OM606 - baldur - 07-14-2018

Yeah you won't get good compression test numbers without a good battery.

RE: Compression tested my junkyard OM606 - supracrazy - 07-14-2018

You would try to start and warm up the motor before doing a compression test. Or just try a wet compression test to see if cylinder 4 increases in compression. Could just be a ring not sealing correctly since it hasn't been ran in awhile... suck about the glow plugs

RE: Compression tested my junkyard OM606 - Granfatherglock - 07-15-2018

(07-14-2018, 07:12 PM)baldur Yeah you won't get good compression test numbers without a good battery.

It is a good battery, Exide 700CCA AGM.

(07-14-2018, 08:37 PM)supracrazy You would try to start and warm up the motor before doing a compression test. Or just try a wet compression test to see if cylinder 4 increases in compression. Could just be a ring not sealing correctly since it hasn't been ran in awhile... suck about the glow plugs

Thanks, I wish I could warm it up first. I thought about trying to get some water in it and plugging in the block heater, but I doubt the block heater will get it warm enough to make a difference. I'll get wet compression numbers as well.

RE: Compression tested my junkyard OM606 - baldur - 07-15-2018

(07-15-2018, 09:35 AM)Granfatherglock
(07-14-2018, 07:12 PM)baldur Yeah you won't get good compression test numbers without a good battery.

It is a good battery, Exide 700CCA AGM.

(07-14-2018, 08:37 PM)supracrazy You would try to start and warm up the motor before doing a compression test. Or just try a wet compression test to see if cylinder 4 increases in compression. Could just be a ring not sealing correctly since it hasn't been ran in awhile... suck about the glow plugs

Thanks, I wish I could warm it up first. I thought about trying to get some water in it and plugging in the block heater, but I doubt the block heater will get it warm enough to make a difference. I'll get wet compression numbers as well.

If it was cranking over slowly you either have a bad battery, a bad starter, bad wiring between them or a practically seized engine.

RE: Compression tested my junkyard OM606 - Granfatherglock - 07-15-2018

[quote pid='88677' dateline='1531665304']

If it was cranking over slowly you either have a bad battery, a bad starter, bad wiring between them or a practically seized engine.
[/quote]

Battery and cables checked out good. You're right it could be the starter or a mechanical fault in the engine. That's what I'm trying to figure out with the compression test, haha.

I added a few drops of oil to 1-4. The engine turned over much better this morning, and #4 jumped up to about 220psi. Which, while still not excellent may show some promise for this this engine. I think it has sat for a very long time and the rings are stuck. I may regret it, but I think I'll hold on to this engine. At the very least it will be good for parts.

I do appreciate your help.