BLOWN engine? he says fuel mixed with oil, and it seized? - Page 2 - PeachParts Mercedes-Benz Forum

Stevo · #16 03-12-2007, 04:13 PM

Quote:

Originally Posted by bgkast

Now that you mention it I have heard that too, but only in WVO systems that use an electric pump behind the stock mechanical one. Seems like the cause was a torn diaphragm in the stock pump. With no electric pump it seems like the car would die before any significant contamination occurred though.

I dont think I've heard of many of those pumps going south. I spoz you would eventually notice the black color in the primary fuel filter

bgkast · #17 03-12-2007, 04:27 PM

The diaphragms probably were damaged by the use of an additional pump.

Stevo · #18 03-12-2007, 11:48 PM

Quote:

Originally Posted by bgkast

The diaphragms probably were damaged by the use of an additional pump.

One of these days when I have nothing too do i will pull one of those pumps off a parts car and see whats inside.

psfred · #19 03-13-2007, 05:00 PM

It's possible, although fairly rare.

If the IP plunger seals fail, or the seal on the lift pump (the one that pumps to the fuel filter, not the hand pump) fail, diesel fuel will get into the sump on the injection pump, and since 1973 or so they are oiled from the crankcase. Bad enough leak, thin oil, hot day and lots of load, seized mains, scored cylinder walls, etc.

Always accompanied by VERY low oil pressure (0 at idle and less than 1 bar at speed, I'd think), so anyone who watches the oil pressure gauge won't get caught, but....

Peter

aklim · #20 03-13-2007, 10:20 PM

Seized, meaning what? It will not turn over at all or that the engine is locked up tight and cannot be turned? In one case, it could be a bad battery,starter or switch and wiring or all of them. In another, the thing will not turn over even if you manually turn it. Probably not making myself clear but can you turn the crank? If you can, it is not seized.

blankenship · #21 05-03-2007, 11:53 AM

hey there. original poster / thread starter here with an update.
well, i put this aside and fell out of touch with the owner of the "seized" benz, but talked to him again finally yesterday asking for more info.

THIS is what he said: "The lift pump died, and after fixing it i didn't change the oil. Well, i guess when the pump died diesel got into the oil and so it thinned the oil and seized. I have been told it would be possible to get going again but I haven't tried."

so, make more sense now? and does that mean it's toast?

and, also, if it IS toast, and not worth fixing (it's pretty ugly), can i take the tranny out of it (a '79 non-turbo) and put it in my '85 turbo? how about the steering box? (i've never been very clear on model year interchanges....)

bgkast · #22 05-03-2007, 03:36 PM

If you are interested in the car I would take a look at it, see if you can turn the engine with a 27mm socket on the crank nut, and do a compression test if you can turn it. If it's seized or has poor compression then it is probably new engine time.

The auto transmission in your '85 is different than the '79 transmission. Only other '85s will have an identical transmission. Older ones would bolt up, but it would be a hassle to convert all of the transmission controls over to the older style.

Stevo · #23 05-03-2007, 06:35 PM

"THIS is what he said: "The lift pump died, and after fixing it i didn't change the oil. Well, i guess when the pump died diesel got into the oil"

This is the first time I have heard of this happening with a 617/6

I think I could say its not a common occurrence??

kip Foss · #24 05-03-2007, 08:37 PM

Steve,

Unlike older US cars where a broken fuel pump diaphragm can flood the crankcase with fuel, I don't think that a leak in the MB lift pump will allow fuel into the crankcase. The fuel lift pump on my 1975 300d is mounted to the back of the injection pump. It has no direct connection to the crankcase. Unless the seal between the lift pump failed and then the seal on the engine side of the IP failed there is no way fuel can get into the crankcase.