Shop says I need a new engine...300E - PeachParts Mercedes-Benz Forum

sptt · #1 05-17-2011, 07:46 PM

I was driving to work this morning going up an incline and strangely enough, the same incline I had this happen before on, the engine overheats (it's not even a steep incline)! I had just replaced the head gasket 1200 miles ago with no loss of coolant or oil since. When I pulled over, the only place I was losing coolant from was the expansion tank overflow hose. Any idea what may have happened? I had the car towed into a friends shop and he just called and said there are two cylinders with no compression and that I need a new (used) engine. I am about to part ways if so...

#2 05-17-2011, 08:08 PM

How hot did it get? Was it in the red, and if so for how long of a time. It could be the head gasket failed on you again. From that I would hesitate to think the whole engine is toast!

JohnM. · #3 05-17-2011, 08:11 PM

I don't see under the circumstances you describe, how you could lose full compression on two cylinders out of nowhere. Is there any coolant/oil mixing? I'm suspicious. How good is this friend?

sptt · #4 05-17-2011, 10:34 PM

My guess is that I need the head redone and not a new engine based on what I've read here in the past. There were no external leaks prior to this happening and everything was fine. I was driving 130 miles round trip and checking fluids daily. It was starting and running great!

When I noticed it was hot, I don't know how long the gauge had been in the red but it was pegged there. I was able to coast downhill while manuevering though traffic to the shoulder and it wasn't acting or sounding bad but I guess that doesn't mean anything.

JohnM. · #5 05-18-2011, 12:06 AM

See if you can do a leakdown test, those numbers would be more valuable than the compression right now. If you don't know how long it was in the red, that's not a good sign for the engine.

sptt · #6 05-18-2011, 12:32 AM

yeah, you're right John. I'll have to see what he comes up with engine wise. My searches have been 1000K + for a used one. Any ideas? I always scan my dashboard but didn't notice how long it had been running since no light popped on and everything felt normal. I just happened to notice the needle pegged to the top when I checked the clock and car was behaving fine. I didn't even have smoke until I pulled over and stopped and then a little started coming out on the expansion tank side and not a lot more after I opened the hood.

tbomachines · #7 05-18-2011, 12:48 AM

M103s are easy to find, you can easily find them for 500 bucks or less. They're used and haven't been rebuilt but lots of guys are parting out these cars

sptt · #8 05-18-2011, 01:28 AM

That would be great if I can find one for that price!

long-gone · #9 05-18-2011, 03:11 AM

My guess would be that it's the result of hand sanding the old head gasket off with 200 grit sand paper and/or the mineral concretions that you described were clogging your water jackets. If you could see openings that were visibly obstructed then it's likely there were obstructions in other places out of view.
Did you do a good coolant flush afterward?

The head could probably be properly resurfaced at machine shop, but if you used the sand paper on the block too that might be a big problem. Otherwise, while these engines aren't immune to ringwear, they have a notoriously strong bottom end. Unless there was some kind of piston damage to those mentioned cylinders, a refurbished head, a new (carefully done, not hurried) head gasket and a thorough coolant flushing might bring it back to use again.
I think I remember you mentioning that you could see evidence of coolant leaking into a cylinder or two when you had the head off, was it the same cylinder/s that the shop say lost compression?

All that being said, if you can find a used M103 for $500 or less (and I agree that's very possible) it might be cheaper and easier to go that route. Be aware though that any used M103 you get might be just a few thousand miles from needing a new head gasket as well.

Ferdman · #10 05-18-2011, 06:45 AM

sptt, it's odd the low coolant level warning light didn't illuminate during this overheating/loss of coolant incident. If your friend isn't a MB-trained tech I would have an indie who is evaluate the condition of your engine, and propose the most sensible and cost effective repair method. If the indie has a borescope he can remove the spark plugs and inspect the cylinder walls to see if any cylinder walls or pistons are toast. Pulling the head will reveal head gasket failure or valve problems.

As mentioned any blockage of coolant passages is undesirable so that's a major consideration befoe deciding to repair your existing engine. On the other hand buying a used engine has a downside since you probably won't know its service history, and it may require major repairs in short order.

vstech · #11 05-18-2011, 10:47 AM

which car? what engine? 2.6 or 3.0?
I have a 90 2.6 running when wrecked, for 300 if you want it. I'll crate it up and have it ready for you.

#12 05-18-2011, 01:01 PM

Overheating an engine is always undesireable, but it doesn't necessarily finish it. Beings the radiator hose didn't burst, and immediately out of water is better. Kind of only you know how hot it was like if it wasn't pinging or knocking. If the rings didn't get hot enough to loose their flex on those cylinders, it could possibly eliminate the bottom end. Once you take the head off, and have it magna fluxed it will tell you if it is good or not, and if you are going to have to replace any other components in the head. Beings you had top end trouble before & all it could be like rolling the dice as to fixing the existing engine or replacing it with a good used one. Price wise and all it might just be a toss-up.

atikovi · #13 05-18-2011, 03:02 PM

Did you have the head shaved and block checked for flatness before replacing the HG? If not they may have been warped and all you would need is to resurface them and replace the HG.

sptt · #14 05-19-2011, 12:19 AM

VSTECH...it is a 1991 3.0

I don't suppose it would work would it?

Also, yes...there was a ton of corrosion when we took the head off and who knows what else was left in there that we didn't get out. We flushed the you know what out of it, but before that, used compressed air to blow out all of the crud in the head and bottom that we could. I think that this car has had several owners so who knows what else was in there? Also, it could have very well been the hand sanding and a warped head (we measured with some tools my friend had from his shop but who knows for sure). I just didn't have the option at the time to get the head skimmed or the money, and I still don't. I was hoping to get at least a little longer out of that job so now I will keep hunting for a better price as I just don't want another new car payment just yet!

Thanks for all the input. I have a rental car right now and it doesn't even come close to the ride or quietness of this car.

JohnM. · #15 05-19-2011, 12:27 AM

Wow. If the block surface was corroded? That is bad news. You should never even take sandpaper to the block, the sealing surface is that sensitive. And if the head wasn't skimmed by a machine shop....surprising it's made it 1200 miles! So yea, new engine time most likely.