Oil burning problem
 

Hello All,
I had a head gasket leak on my 84 300D that had been slowly puking coolant since I bought the car. Last January I pulled the head and discovered the head gasket was indeed compromised. Since I had the head off I disassembled the head and dropped it off at a reputable shop that does a lot of diesel work. The exhaust guides needed to be done so I had them replaced. Valves were ground and all new seals, gaskets, etc. were installed when it all went back together. The head gasket repair worked, no longer pukes coolant and system doesn't retain pressure. Before the head work the engine used 1qt of oil every 3500-4000miles. Now it uses 1qt every 200-400miles. I have used the car very little since the work and the fact that I was busy replacing/repairing the AC system. Now that is almost all done I am trying to figure out what to do about the oil consumption. Obviously something went wrong. I figure maybe a guide didn't install correctly, etc. I have rebuilt many heads and I used the MB manual, etc. when it all went back together. The guides and seals were OE MB parts. So what do I do now? I don't really want to take it all apart again. I am tired of working on this car. I would consider just swapping a new/rebuilt head on if the price was right but the rebuilts I have seen from Metric Motors, etc. are quite pricey. I cannot stomach tearing it all apart and trying to fix it again only to make the same mistake, again. This really irks me. I am also just putting the car up for sale, as is, as I just want out at this point. Any input on a good rebuilt head source would be appreciated. Thanks, RT

not to be
 

too obvious but i didnt see where you checked it for warping.

sorry to hear of your lack of success. maybe still something simple overlooked. doesnt make sense that it used little before and so much now.

dont give up yet!

tom w

Funny you should mention this today.

I'm still struggling with my head situation, nearly eight weeks after removing it.

The head was cracked and, thanks to Jim, I have a replacement.

But, the local shop has proven that they simply are not up to the task. Just insufficient knowledge of what to do, and a refusal to start on the head and work it until it is finished.

So, I'm pulling the plug.

The cost to have Metric motors do the complete job is $380.00. This includes valve guides and valve seals. Since I already bought these from the dealer, the price will be less (I'm thinking about $300). This is $150. less than the local yokel.

The cost to ship the head and a heavy wooden crate out to CA is about $60. each way.

I'm going to do it. Enough of keeping my fingers crossed and hoping that this imbecile doesn't cause more damage. If Metric does it, it's cheap insurance, IMHO.

It's somewhat surprising, however, that your oil consumption issue can be caused by valve guides, especially since they were replaced. Were the valve guides OE? Some are cautious of aftermarket guides due to random quality. There is not much tolerance between the valve and the guide. What about the valve seals? Were they OE parts? If not, that could be the issue.

Are you sure it's all coming out the exhaust? Nothing on the ground? If so, is it burning coolant too?

Definitely not using coolant. Used all OEM parts. Machine shop said head was flat/straight. Brian, let me know all the info on contacting Metric. I may go that route too. Oil smoke is definitely out the exhaust. None on the ground. Clearly visible blue smoke when driving behind car and a pungent burning oil smell. I thought maybe the turbo seals had gone but that seems awful coincedental with the head work. As a quick check I also ran the crankcase vent to atmosphere to make sure it wasn't blowby and it still smoked. I'm beginning to hate this car. RT

Don't completely discount the turbo seals.

I've been wrestling with an oil consumption issue on the SDL. It's running about 1 quart every 1500 miles. Very little blowby. Oil smell in the vehicle, in the trunk, and in the exhaust. I believe that it's leaking into the exhaust and burning off in there.

If the oil was burned in the combustion chamber, in my case, 1500 miles equates to over 215 quarts of fuel. To this we add 1 quart of oil. So, the ratio is 1: 215. I don't think you could smell this in the exhaust, and, you certainly would not smell it in the vehicle.

But, the interesting point, and the reason for the post, is the fact that the situation gets far more pronounced after an oil change. I can't explain it, but there must be some additional oil pressure that forces more oil to the turbo and more leakage occurs, and more oil smell is present. So, if the valve guides caused an increase in oil pressure to the turbo, a slight leakage might be increased significantly.

I'm just tossing this out there, because valve guides and valve seals make no sense, unless one of them fell out. You have so much oil going through the engine that it has to be an obvious mistake if the head is involved.

Seems like there has been some talk on the forum here that suggests clearances for the guides should not be set at values considered good for Domestic engines!! You might want to check with the shop to see what specs they used when installing the guides.

I vaguely remember reading the same thing. I think the engine manual provides the specs for the clearance between the valve stems and the guides and they are tighter than for a domestic car.

This is true. The FSM provides specs for valve stem OD, guide ID and OD, press force installing guide, guide position (press to depth), and then lateral movement of each valve in installed guide - with valve x mm out from seat, it can't be allowed to wobble more than Y mm in any direction.

I used new aftermarket guides, seals and exhaust valves. When I put on the first seal, I did it wrong, and remember thinking, "gee, there are several ways to mess up the installation of these seals that really isn't that obvious".

My point in this ramble is that I'm venturing a WAG that there's a problem with the valve seals. If you have no problem with your coolant, you probably got the head gasket right, so I doubt the oil is getting through there. You should be able to check these without removing much more than the valve cover. Those seals (it's coming back to me a little now) have to be pushed down pretty darn hard until they seat in the rounded groove ground in the top of the valve guide. The feedback on how this felt wasn't (in my opinion) very satisfying. Frankly, I'd be very surprised if this wasn't missed by a lot of very compenent mechanics.

Lastly, boy, do I ever know that gut wrenching feeling of so close but so far. I came pretty close to giving up after completely rebuilding my 617. The feeling of hopelessness at not being able to solve my low power/huge smoke problem was pretty rotten. However, the good feeling of finally conquering it (horribly mistimed IP) hasn't worn off after more than a year. I hope you find it, and, I think you will.

That's exactly what I was thinking- stopping a leak in one place would cause an additional pressure load and would stress anything else that was borderline and make it leak. I wouldn't give up on the car, just walk away from it for a bit then go back to it when your frustration subsides.

I really don't see how the valve guides could cause an increase in oil pressure since they are not part of the pressurized lubrication system. Besides the oil pressure is no different than it ever has been. I remember replacing the valve seals quite clearly and it did take a lot of pressure to make them seat and snap on to the top of the guide. I was very careful with them. Additionally the valve clearances were much tighter after the valve job than when I disassembled the head. I did the reassembly and I remember quite well. I just got a line on a career MB lead mechanic at the local very large MB dealer. He is in his 50's, been doing MB's for years and does work on the side. Hopefully he will be interested. My plan is to simply give the damned car to him and pay him cash when he needs it. RT

After mulling about your response all night, Rob, I have to agree with it. The tighter guides won't raise the oil pressure. So, the only possibility is that one of the seals came loose in some way. I can't see anything else related to the work you have done on the head other than a bad head gasket. This seems like a very remote possibility, but, if something went wrong on the gasket between one of the oil passages and the combustion chamber, the pressurized oil would flow right into the cylinder and burn with ease.

It's a remote possibility, but, I can't think of anything else.

At this rate of oil consumption, do you see any visible smoke in the exhaust when warm? I'm curious as to the point where visible oil smoke appears.

BTW, I removed my replacement head, and all parts, from the yokel yokel and shipped it to California via Fedex Ground. $60 and it will be there in four days.

i think
 

that it must be the head gasket or a bad job on the valve guides. i dont think the seals even if they were all completely missing would cause that kind of consumption.

and the turbo doesnt seeim likely either.

my $.02

tom w

Can you offer any scenario whereby brand new OE valve guides could cause this level of consumption? I'm asking point blank, because I cannot.

only if
 

they were completely wrong or loose.

tom w