Testing a out-o-the-car engine - PeachParts Mercedes-Benz Forum

#1 11-29-2005, 07:02 PM

Howdy all...

A while back I posted some issues I was having with my '84 300D. Thanks to the board, I narrowed the problem down to likely being a cylinder/piston issue (or maybe a head gasket). Around the same time as this, a thread was posted regarding a 150k mi engine for sale on eBay that didn't get bid on. Long story short - the engine was in NH (I'm in ME), I talked with the guy, everything seemed on the up and up, he wanted to get rid of the engine rather than let it sit outside for a winter and I gobbled it up for $300. Apparently the car that was its home was in a nasty sideswipe.

So I have this engine on the back of a pickup truck and want to do some diagnostics before installing it in my vehicle. My cousin said he did a compression test on his VW van by manually turning the engine. I searched the archives but couldn't find anything. Is this a possibility. What else would you suggest doing to the engine to check it before putting it in the car?

WANT '71 280SEL · #2 11-29-2005, 07:26 PM

I wouldn't worry too much about testing it before it goes in. If anything, start replacing those hard to get to gaskets now while it's out so you could have the only 617 on the board that doesn't mark its spot wherever its parked. The oil filter housing gasket and upper oil pan gasket come to mind. Just look at it and try to figure out where the oil that is leaking might be coming from.

I don't know if a compression test would be very accurate without the starter motor doing it. You're not going to be able to hand crank it over fast enough to build enough compression. They generate compression when they're being spun over fast, not slowly with a ratchet.

If you wanted to check it out there are ways, but those ways would involve pulling the head, etc. Actually, this summer I'm hoping to pull my engine just for the purpose of resealing it. I'm sick of the small oil leaks, they bother me the most about any car next to body condition. So hopefully I can get the rust fixed and body painted while I'm resealing the engine.

Thanks
David

t walgamuth · #3 11-29-2005, 07:33 PM

and get a good compression test out of the car. i would do it unless i could have heard the engine run while still in the donor car.

tom w

Stevo · #4 11-29-2005, 07:57 PM

I cranked a 616 over with the starter while sitting on a dolly in my shop, Humm... that could be taken a couple ways, anyway i did a compression test for what it was worth, maybe, not much. You can check chain stretch and clean her up nice.

t walgamuth · #5 11-29-2005, 10:01 PM

no reason you cant start and run it in the truck bed. be sure it is upright though. no water is ok for a few minutes but not no oil.

tom w

#6 11-30-2005, 09:22 AM

As I'm reading some of this I'm thinking about a diesel I had with ONE bad motor mount! Isn't that thing going to walk the entire bed of that truck if I turn it over?

I may try a compression test, if I can get the right adapter for the glow plug hole.

#7 11-30-2005, 03:15 PM

Unless it's got a manual tranny flywheel, you are going to have a tough time getting it to idle/run properly without the added mass of the torque converter.

KCM · #8 11-30-2005, 06:33 PM

Started an OM617 out of an automatic 300D turbo last year. Set it on the ground with the engine hoist hooked up for stability (think I blocked up the side engine mounts too), hooked up a fuel line (bled the lines of course), and it started right up. Ran smooth even without the torque converter, and without the turbo or exhaust manifold attached. If you want to run it longer, plug the bottom radiator port and fill the engine with water (bleed out the air from the engine to make sure it is completely full of water). A diesel will run a while full of water and not under load without overheating.

RUN-EM · #9 11-30-2005, 09:41 PM

Yeah, fire the sucker up. Just be sure and get videos of this. You might qualify for the commercial with the chevy engine leaping out of the truck and scampering down the street searching for its favorite oil. Or you might be able to red line it and get on Americas Funniest Videos

YowwZa. Add a little gasoline to the fuel - say 40 to 50 percent for the pyrotechnics effect. OR better still, crank up the fuel AND add propane injection to the lil bomb

We will all be watchin the nightly news for the results

Regards

Run-em
1983 300 S D - aka- SPARKY THE DIESEL

gdemoss01 · #10 11-30-2005, 10:40 PM

But isn't the oil circulated through the oil cooler. How would you run a diesel without the oil cooler. I have an engine sitting on a hoist at the moment and might one day try and start it but don;t have a clue as to how to do it. Except of course have a starter and a battery hooked up to it and maybe a remote starter switch, and some diesel fuel.

Can anyone explain this to me in more detail?

Rev. Dr. G.

t walgamuth · #11 11-30-2005, 10:48 PM

on the oil cooler. without that you wont have oil pressure (unless it has an oil thermosat). someone will chime in on the stat idea. i am not sure. i wouldnt want to srart it unless it has oil pressure. i dont think.

tom w

Tirebiter · #12 11-30-2005, 11:53 PM

Much easier to run a cylinder leakage test on it.

stayalert · #13 12-01-2005, 10:11 AM

What else would you suggest doing to the engine to check it before putting it in the car?

I would remove, clean threads, antisieze, and reinstall pretty much any bolt (starter, block heater, block drain, etc) that I could get my hands on. I'd rehab the hanger for the turbo oil drain tube, and prolly repalce a few seals/gaskets as others have mentioned above....Where in Maine are you?

KCM · #14 12-01-2005, 05:32 PM

Quote:

Originally Posted by gdemoss01

But isn't the oil circulated through the oil cooler. How would you run a diesel without the oil cooler. I have an engine sitting on a hoist at the moment and might one day try and start it but don;t have a clue as to how to do it. Except of course have a starter and a battery hooked up to it and maybe a remote starter switch, and some diesel fuel.

Can anyone explain this to me in more detail?

Rev. Dr. G.

When I started mine, I had an oil cooler hooked up to it. Don't know if the lines can be blocked and ran with out it. But NEVER run an engine without oil pressure. You will also need to block the oil guage line, or attach a guage to the line.

Isn't much to starting a diesel. Just hook up the fuel source to the inlet of the side delivery pump on the main injection pump, then bleed the system with the hand pump. You will need to run a return line back to the fuel source from the injectors. Hook up a battery and remote starter button to the starter. Then just start the engine and control the speed with the throttle lever on the injection pump. On the Mercedes, you will have to idle it way down to shut it off, or apply vacuum to the vacuum shut-off diaphragm at the rear of the injection pump.

#15 12-08-2005, 07:48 PM

Days later....

I have everything all set and ready to run. I jumped to the metal tab sticking up out of the starter. I can hear it spin, but it's not engaging. I swapped the starter from my own block, so I know it works. Any ideas? Am I jumping it at the right point?

And Stayalert... I am in Pittsfield, ME.