300SDL Stuck engine with bad noise and vibration when cranking. - Page 2 - PeachParts Mercedes-Benz Forum

AUDIBLE · #16 10-27-2011, 02:13 PM

Thanks for the interesting ideas, never heard of hydrolock before.

I didn't mention that earlier in the process, I removed the radiator for access. The coolant was clean and there was no trace of coolant in the oil when I drained that. (The car HAD been losing coolant, but I could never find where, other than at the coolant reserve tank. It had started to run hotter, especially in traffic and up hills, so month or so before this sticking problem, I replaced the thermostat and citrus flushed the cooling system. There also seemed to be a problem with the aux. fan in front of the radiator, in that it didn't come on or stay on in response to engine temp, and would also sometimes come on and stay on when I didn't expect it to.)

But since both oil and coolant were clean, I'm not sure where that leaves me. Back when this started, the engine was still stuck AFTER I had drained the coolant and removed the radiator.

Thanks again
Bruce

barry123400 · #17 10-27-2011, 02:48 PM

I would do all the tests possible to check out the head gaskets integrity. It is now the most probable suspect.

Since you have been losing some coolant right along one of the injectors tips might look cleaner and the pre chamber as well to some extent. Adding coolant to that cylinder with a leak may have steam cleaned everything in that cylinder over the last while before it became serious.

What to me proves the hydrolocking is you got almost two turns on the engine before it stopped up. On one rotation of the crank the valves would be open. The next rotation closed and the fluid would be trapped.

It was just luck where you started turning. Or by turning to the stop point each way you where going by the open valves each time.

I still always like to identify the cylinder impacted with any problem before removing the head. In your case the coolant will have left evidence. If your fault had been actually mechanical it would not have cured itself no matter how long it sat.

AUDIBLE · #18 10-27-2011, 04:34 PM

Thanks, I'll start looking into the gasket. It sounds like what you are describing quite a bit of coolant, that is, enough to partially fill the cylinder on the intake stroke so that the compression stroke would push the water all the way to the top, where it couldn't push any more. Is that the idea? Would you use a compression tester to see how well each cylinder holds?

A great help, I appreciate it.

Bruce S.

bigblockchev · #19 10-27-2011, 05:29 PM

Either one of these could leak coolant into the combustion chamber without leaking into the oil passages or exhaust into the coolant. I suspect that as has been suggested if you pull the injectors one will be real clean, you might even get coolant squirting out when you crank. It doesn't take very much coolant to hydrolock, fluid is essentially incompressible so the piston might as well be hitting a block of metal. Cheers Dan

AUDIBLE · #20 10-27-2011, 08:11 PM

So I looked at all the injectors, but since I disassembled, inspected and cleaned them a few thousand miles ago, it's probably no surprise that they all looked the same and were all clean. Now on to more searching for gasket or head crack. The head was rebuilt less than about 20K miles ago, with a new gasket at that time, obviously. It was done by Mr. Mercedes in Encino, who has a good rep., so I'm thinking it was done right.

Bruce

AUDIBLE · #21 12-07-2011, 08:58 PM

Finally got back to the mighty SDL. Couldn't determine for sure whether there was a bad gasket or head, but saw no symptoms of either, and since the motor was unstuck, I cleaned everything up, put in a new crankshaft front seal and Vac. pump gasket, re-assembled, and it runs about like it did before all this trouble. Except for one thing. It now leaks oil from the front of the engine much worse than before the hydrolock happened. When it was apart, I didn't see any evidence that the timing chain cover was leaking, so my only suspect is the crank seal I just replaced. It sounds like I should start a new thread?

thanks
Bruce S

AUDIBLE · #22 12-24-2011, 02:21 PM

I've been running the car for a couple weeks since freeing the original hydrolock and fixing the various oil leaks. This morning it hydrolocked again. Both times it has been in the morning. I'm guessing that is because turning off the engine when it's hot pushes coolant into one or more of the cylinders. Since I knew what it was this time, I loosened all the injectors except the one under the intake manifold. Turning the engine over cleared the problem. Because I've drained and refilled the coolant several times in the last few weeks, I'm not sure how much coolant is leaking, or from exactly where. I haven't seen coolant in the oil, but since it would sink to the bottom, perhaps I wouldn't see it anyway. Will watch the coolant and oil in the next few weeks to monitor consumption.

Assuming that I have a bad head gasket, am I running a big risk running the car this way, for instance, could it hydrolock when running and destroy itself if the gasket leak gets bad enough?

Also, are gasket-sealing additives a non-starter in this car, even for a short-term fix?

thanks again everyone!
Bruce

bigblockchev · #23 12-24-2011, 02:37 PM

Coolant or water in the oil can destroy the bearings and crankshaft. I would be pulling the head to repair the leak before it does some additional damage. The risk is that some sort of mechanical damage can break things like the crankshaft . This pretty much renders the motor unrepairable or at least highly suspect. Cheers Dan

barry123400 · #24 12-24-2011, 08:13 PM

You may have missed the opportunity to see what cylinder it was when you pulled the injectors and cranked over the engine. Some fluid must have been expelled or at least an abnormal mist .

Unless there was time for the fluid to get past the rings before you got the injectors out. Takes two people to do the test. One at the key switch and one watching for mist or spray under the hood.

ah-kay · #25 12-25-2011, 01:00 AM

Disclaimer - I did it to my car but the result may varies.

The reason I suggested Hydrolocking is I experienced it. Coolant leaked back into the cylinder and the engine would not turn over. Actually another member had the same problem in this thread.

Blue smoke puzzle

He PM me to tell me that I am right on the nail. I did not replace the HG and I have the car fixed and I have done 1000 miles on the car since. I use the Blue Devil HG sealant to seal the HG. Blue Devil has very good write up and it is only $30. So there is nothing to lose and everything to gain. You need to follow the instruction to the letters.

1K miles is not a lot and the jury is still out. So far I have no smoke, no hard radiator hose in the morning, not losing coolant and no hydrolock. It is worth a try in my opinion if you do not want to open up the engine.

Good luck.

btw: please refrain from telling me not to use snake oil.

tram · #26 12-25-2011, 03:02 AM

I'm wondering if it could also be hydro- locking on oil or diesel fuel. Leaky or malfunctioning injector?

AUDIBLE · #27 12-25-2011, 12:10 PM

thanks for the comments.

I figured out that I blew the cylinder-hydrolock diagnosis right after I finished. Nice.

I tired lifting the purple wire from the GP circuit as suggested above. I'm not sure how much of an improvement it made. A seasoned Mercedes mechanic told me to start up at 2000+ rpm to avoid smoke. This does work, if I keep the rpm's above about 1600, and if I sit there for 4 minutes waiting for the block to heat up.

I wondered about the diesel fuel hydrolocking as well. Seems that it would be easier to overload a cylinder with fuel from an injector than from a gasket leak, but I have no facts on my side. I do know that the injectors are out of whack by the nailing and unburned fuel. I've never smelled anything like coolant in the exhaust.

Can a cylinder fail to ignite because too much fuel is sprayed, as opposed to just a bad pattern?

Will advise about changes.

Thanks!

ah-kay · #28 12-25-2011, 02:16 PM

You need 2 things to hydrolock by diesel fuel

1) The injector is leaking like a sieve.
2) Engine has to be spinning to dispense the fuel.

It is very very unlikely IMHO. I have no doubt it was coolant in my car. I removed the injectors, turned the engine by hand and coolant sprouted out like a fountain all over me.

I have nothing to add to this thread. Good luck with whatever you decide to do.

whunter · #29 12-25-2011, 07:38 PM

Quote:

Originally Posted by AUDIBLE

thanks for the comments.

I figured out that I blew the cylinder-hydrolock diagnosis right after I finished. Nice.

I tired lifting the purple wire from the GP circuit as suggested above. I'm not sure how much of an improvement it made. A seasoned Mercedes mechanic told me to start up at 2000+ rpm to avoid smoke. This does work, if I keep the rpm's above about 1600, and if I sit there for 4 minutes waiting for the block to heat up.

I wondered about the diesel fuel hydrolocking as well. Seems that it would be easier to overload a cylinder with fuel from an injector than from a gasket leak, but I have no facts on my side. I do know that the injectors are out of whack by the nailing and unburned fuel. I've never smelled anything like coolant in the exhaust.

Can a cylinder fail to ignite because too much fuel is sprayed, as opposed to just a bad pattern?

Will advise about changes.

Thanks!

Warning...

If it is a head crack or gasket issue, and you keep running the engine; major damage will happen..

Hydrolock - Wikipedia, the free encyclopedia

OM617 head gasket failure - pictures

What causes pits in the cylinder head?

Cavitation

Diesel cylinder head issues thread

hydrolock damage engine - Google Search

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barry123400 · #30 12-26-2011, 10:54 AM

Yes the number 14 heads are what they are potentially cracked up to be as well. You should do the cold hose test on that engine . Is the hose hard the next morning or flacid?

You do have to get out of bed to check the upper coolant hose. Unless you are sleeping in the car I suppose. It is kind of an inverse proportion type of thing so do not get confused. The car works best with the hose flacid the next morning. You do not.

I have to thank Mr.Hunter for reminding me that you have the notorious possible #14 head engine. I gotta stop drinking in the mornings as well.