1985 300TD head gasket repair - Page 4 - PeachParts Mercedes-Benz Forum

Chad300tdt · #46 09-26-2012, 10:25 PM

Quote:

Originally Posted by pwogaman

I'm surprise to see that on a 617 head. Did you get a baseline compression?

I haven't done anything other than clean it. If it passed a compression test would it be worth using this head?

Know where I can get a replacement?

pwogaman · #47 09-26-2012, 11:18 PM

I don't have any idea to what extent cracks grow on 617s, but we know at least these grew to the point pictured. I can't think of any reason to believe they woud have stopped doing so at the point you took the pictures. It is possible though.

Procedurally, it is possible to grind out the crack, weld in some new stock, and then shape to dimension. I believe you would need to heat treat it after and that introduces the possibility of warping he head.

As far as gettng a replacement, there is usually at least one OM617.96x engine in the Crazy Ray's locations in the Baltimore area.

whunter · #48 09-27-2012, 12:49 AM

Quote:

Originally Posted by Chad300tdt

So I spent some time cleaning the head today.
I found 2 cracks on the second set of valves from the rear. Those are the only cracks on the whole head.

So does this mean I need a new head now?

Remove the valves on that cylinder.
Clean the port, looking for additional or continuing crack.

I will start looking for another head for you..

.

Chad300tdt · #49 09-27-2012, 10:14 AM

Quote:

Originally Posted by whunter

Remove the valves on that cylinder.
Clean the port, looking for additional or continuing crack.

I will start looking for another head for you..

.

I just removed the valves and cleaned everything up. It was very difficult to get decent pics, but these are pretty good. I made the outline come to a point near where the cracks end inside the port.

If I fogged the area with my breath, the cracks were much more evident.

barry123400 · #50 09-27-2012, 10:14 AM

Great job of cleaning that head down. It in my opinion it is far easier to find a good used head for your engine than on the later engines.

Easy enough you do not have to jump on the first one you find. Make the purchase contingent on no cracks or warpage. Or they give your money back. Also check it for flatness as you should with any head.

These heads are not notorious for warping . You only have a very small amount of metal removal allowance to true up one of these heads if it is. Only about three thousands maximum I think. Six one seven heads are not prone to easily crack either.

It is still not unknown for one of these heads to be cracked..In general regardless, they are still a very strong design as heads go.

Probable or possible cause of all the cracks is Operator error. The engine comes in off a highway and is shut right off for fuel for example. Hot spots in the castings have not had time to adjust and equalise. In fact the coolant in the immediate vicinity of the hot spot may boil away from it when coolant circulation is stopped. This causes different shrinkage rates of the metal to occur. Adjacent areas are still in contact with the coolant where the hot spots tend to cool much slower. Over time this localised stressing results in cracking. Your exhaust valves in most cylinders have stopped the frequent contact as well. Those still in contact with the seats are still adding heat into the casting locally until the cool down.

Or really built up deposits on walls in the waterjackets may also create much of the same senario. I was going to post this a long time ago as one of the factors perhaps in the later more trouble prone aluminium heads as well. .

Much better to let the engine run and equalise any hot spots with the surrounding metal before shutting them down. Perhaps the guys with aluminium heads especially should give this some consideration. The cracks we are seeing in general are not resulting from actual compression pressure stresses..I am pretty sure but not positive I am right. The cool down heat equalization of the heads metal running at idle is a good practice. It is a time thing and will not be reflected in your temperature gauge usually. A few minutes is or should be enough.Even one minute running is far superior to instant shutdown.That the practice will do no harm is pretty logical even if practiced by a non believer. The expansion/contraction of aluminium especially is substantial when considered against cast iron. My guess again without being certain is the improved versions of the problamatic aluminium heads had changes in the waterjackets engineered in as well.

Chad300tdt · #51 09-27-2012, 10:27 AM

Quote:

Originally Posted by barry123400

Great job of cleaning that head down. It in my opinion it is far easier to find a good used head for your engine than on the later engines.

Easy enough you do not have to jump on the first one you find. Make the purchase contingent on no cracks or warpage. Or they give your money back. Also check it for flatness as you should with any head.

These heads are not notorious for warping at least. You also have a very small amount of metal removal allowance to true up one of these heads if it is. Only about three thousands maximum I think.

It is not unknown for one of these heads to be cracked..In general they are still a very strong design as heads go.

Thanks. There is a great deal of cleaning left on this head, but I guess there's no reason to continue at this point.

I went searching last night and found that Metric Motors sells completely refurbished wagon heads for $920 plus shipping and an $800 core charge.

Mercedes Rebuilt Engines

If I get a used head and have it sent out to be checked and have the valve guides done, I imagine I'll be at around $700 provided I can get a really good deal on the used head.

This is all making me think about getting a different engine, but then I have a whole new set of uncertainties.

EDIT: Part number on head - 617 016 04 01. It also had MoCR at the end and an "85" stamped on the other side which I assume indicates the model year.

barry123400 · #52 09-27-2012, 11:15 AM

Quote:

Originally Posted by Chad300tdt

Thanks. There is a great deal of cleaning left on this head, but I guess there's no reason to continue at this point.

I went searching last night and found that Metric Motors sells completely refurbished wagon heads for $920 plus shipping and an $800 core charge.

Mercedes Rebuilt Engines

If I get a used head and have it sent out to be checked and have the valve guides done, I imagine I'll be at around $700 provided I can get a really good deal on the used head.

This is all making me think about getting a different engine, but then I have a whole new set of uncertainties.

EDIT: Part number on head - 617 016 04 01. It also had MoCR at the end and an "85" stamped on the other side which I assume indicates the model year.

If you where not consuming excess amounts of base oil etc. Plus in general the car started well within the typical paremeters of it's type. Changing the head is a better gamble than another engine usually.

You would have to check but the cracks in the existing head to me indicate it may not be eligiable for core credit anyways. Not knowing everything myself you could keep this in mind or already have.

I might consider putting an ad in our parts wanted portion of the forum. Thats if it were me and people trying to help locate one for you turn up dry. Plus none locally. .You would want an uncracked head for the credit anyways if you decided on the expensive option. The economy is sluggish enough you may even be able to work a deal on the reconditioning of a replacement head elsewhere.

These situations present a challenge to any of us when they occur. Initially I was not aware it was a covered wagon head. Of course there are plenty of surplus normal car heads out there.

Chad300tdt · #53 09-27-2012, 12:43 PM

The car only had the coolant leak down into the oil overnight and I drained the oil the very next day when I discovered the problem.

I had just checked the oil and coolant the night before and everything looked OK. When I went out in the morning to check the trans fluid, I noticed the coolant expansion tank was empty, then I saw the oil was WAY overfilled.

EDIT: Before any of this happened, the wagon ran great. Only 21 mpg, but easy starts, smooth idle, great power, small leaks here and there, and not really any unusual smoke.

barry123400 · #54 09-27-2012, 01:13 PM

Should have mentioned just how crude I can do things for myself. Thats if I really think the alternative costs are too high. Or the outcome overkill.

Get a used head. Remove the rocker arms. Invert the head and start by checking for valve leakage using a thin fluid in the valve recess areas. If pretty tight check the head for flatness and clean it down for crack detection.

If these tests are good install the used head as is. If detectng valve seat leakage then negotiate with someone for a valve job. Making sure they are competant type individuals in auto machine work. They really need not have a lot of experience on these particular heads although it does not hurt as long as they are competant.

The only variation I can think of is to consider changing the valve seals out as this allows some evaluation of the valve guides at the same time. If the leakge test went well the probability is that the valve guides are not too bad. Or the seats would have reflected they were.

We are in general talking about the cheapest method of getting back into some sembalance of reasonable serviceability. After all if the rest of the car is not perfect and the intent is not to spend the money to bring it up close to it overall in the picture. It can work out. The lower the accumulated milage on the used head the better.. You could even luck into one where the existing head has not been long in service.

People locally think that I am pretty proficent at locating and dealing with things. The reality is I just turn over more stones and consider where the best options to find them or circumvent them might be first. Since almost no mechanic grinds their own seats anymore there are surplus motorised seat grinders on ebay from time to time very cheap.The only issue with changing your own valve guides is really getting a reamer that is appropiate. Farming out the valves that are still fit to grind should be cheap enough. My old habits of doing things are okay as long as the majority of the population does not as well. The economy would probably fold up if they did. These are just semi entrenched old habits really from my early days when money was scarce. Most mercedes dealers and in fact other brands as well did not farm out valve work. They owned a seat grinder and valve grinder in house. Two hundred dollars or less might get you the two pieces today. Small garages did not in genral plane warped heads though.

vstech · #55 09-27-2012, 01:36 PM

Quote:

Originally Posted by Chad300tdt

Thanks. There is a great deal of cleaning left on this head, but I guess there's no reason to continue at this point.

I went searching last night and found that Metric Motors sells completely refurbished wagon heads for $920 plus shipping and an $800 core charge.

Mercedes Rebuilt Engines

If I get a used head and have it sent out to be checked and have the valve guides done, I imagine I'll be at around $700 provided I can get a really good deal on the used head.

This is all making me think about getting a different engine, but then I have a whole new set of uncertainties.

EDIT: Part number on head - 617 016 04 01. It also had MoCR at the end and an "85" stamped on the other side which I assume indicates the model year.

pull all your valves, and springs, and I'll get the head in my 80TD cleaned up and tested. I'll let you know if it's clear or not. I have a magnaflux shop nearby that can test for any cracks!

Chad300tdt · #56 09-27-2012, 01:40 PM

Quote:

Originally Posted by vstech

pull all your valves, and springs, and I'll get the head in my 80TD cleaned up and tested. I'll let you know if it's clear or not. I have a magnaflux shop nearby that can test for any cracks!

Is the 1980 a NA engine? Will the head from that work on my 1985? I can pull all the stuff to swap, but I thought it had to be a turbo engine. Is the only difference the valves?

vstech · #57 09-27-2012, 01:45 PM

valves and some have suggested that the seats are different, but your pic does not show any hardened inserts. Roy thinks they are the same head, just different cam and valves.

Chad300tdt · #58 09-27-2012, 01:47 PM

Quote:

Originally Posted by vstech

valves and some have suggested that the seats are different, but your pic does not show any hardened inserts. Roy thinks they are the same head, just different cam and valves.

That's AWESOME! If it all works out, I guess I need to visit you and save some shipping costs.

vstech · #59 09-27-2012, 01:49 PM

Quote:

Originally Posted by pwogaman

I don't have any idea to what extent cracks grow on 617s, but we know at least these grew to the point pictured. I can't think of any reason to believe they woud have stopped doing so at the point you took the pictures. It is possible though.

Procedurally, it is possible to grind out the crack, weld in some new stock, and then shape to dimension. I believe you would need to heat treat it after and that introduces the possibility of warping he head.

As far as gettng a replacement, there is usually at least one OM617.96x engine in the Crazy Ray's locations in the Baltimore area.

shops that can weld a cast iron head are EXTREMELY few and far between...
the entire head has to be heated in a brick oven to the welding temp, then welded INSIDE THE OVEN, then allowed to cool EXTREMELY SLOWLY for like 72hours...

NOT CHEAP! brazing can be done, but I doubt it would hold up in a diesel engine...

barry123400 · #60 09-27-2012, 02:12 PM

Quote:

Originally Posted by vstech

shops that can weld a cast iron head are EXTREMELY few and far between...
the entire head has to be heated in a brick oven to the welding temp, then welded INSIDE THE OVEN, then allowed to cool EXTREMELY SLOWLY for like 72hours...

NOT CHEAP! brazing can be done, but I doubt it would hold up in a diesel engine...

There is only one shop in Canada that can pull off almost anything well. They will not even attempt anything unless they are pretty certain it will work out. I seldom have use for them. For what they can do their prices are reasonable as well.Located in Montreal, Canada. It was my understanding that exotic vehicle machine work from right across Canada was their prime area of expertise. The typical cracking in the older bmw fifth cyinder area was repairable at very reasonable costs as well by them for example.

No doubt in my mind that they must also be the largest automotive machine shop company in Canada. My experiences with them have included repair and restoration of damaged expensive to replace or unobtainable cams. They held up in service well.

I have recommended them to different people over the years. This is the place other automotive machine places send things that are beyond their abilities or skill levels in house. Your head casting is not a good candidate for welding by a firm like theirs.. Unless it was absolutly impossible to replace and the engine was worth a fortune. Even then they might decline if they felt other cracks where innevatable. They just have the overall experience to make determinations and repairs that are beyond the average guys comprehension.