My 1987 603A which I installed into my 91 300GD has started leaking oil at the front corner just above the thermostat at the water pump housing.

Could it possibly be the one of the oil passages restricted by the head gasket has broken away? Meaning that corner of the head gasket is not sealing properly?

Yes this is a number 14 head. I have used the balkamp head gasket test and it showed that there are no coolant leaks.

Valve cover gasket is clean and new. No leaks there.

There is no mixing of oil and coolant or coolant and oil.

Any other suggestions? When I swapped motors I installed the updated waterpump housing. Are there oil passages in this install that could cause a leak?

Thanks
Mark

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91 300GD SWB with transplanted 87 OM603 turbo motor

They all do that eventually. Its from the timing chain area and it won't affect compression. There's not enough clamping force there to keep the oil from weeping out in that area.

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CENSORED due to not family friendly words

You will ikely just have to live with it. Changing the headgasket to a new/improved model is the only real way to address it, but this opens op a whol other can of worms in that original heads and more-likely cam shafts have a tendency of cracking on reinstallation or soon thereafter, they are particulalry sensitive to retorquing and must be done correctly...

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Stable Mates:
1987 300TD 310K mi (Hans)
2008 Jeep Grand Cherokee OM642 165k mi (Benzrokee)

Given the oil returns only see splash / low pressure from blow by, try this.

Let the engine sit overnight so oil runs down to the oil pan. Clean the area thoroughly with carb cleaner / mineral spirits / compressed air. When everything is clean, follow up with lacquer thinner as this drys clean. ( Lacquer thinner is a great shop tool for general final cleaning, getting the low end / "spray gun cleaning" quality is fine. )

At the area of the leak, run a 1/4" or so dia bead of silicone on each side of the head to block line then fold the two lines towards each other squishing some into the block / head line. Folding the silicone towards the line gives for a complete seal in case there is any residual oil in the line. The goal is to make a patch over the leak.

You might have to add more to assure the thickness over the line is enough, taper the edges and run along the line far enough to assure the oil just does not follow the line. Let cure overnight and hopefully the leak has stopped / slowed down. If it only slowed down, it might start leaking again in the future, if the leak stopped it should be fine for a good while.

Pick the color of silicone that matches engine color to make the repair less visible. Yes, it looks like a patch up but the cost is minimal and won't cause any collateral damage making it worth a shot.

On various cars that have leak prone oil pan joints, I've run a bead around the entire pan when building the engine to create a leak proof seal.

I like this idea, very clever.

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1987 300TD named Klause
1987 300TD named Spouse
1987 300D named Seabiscuit
1980 300TD names Chloie (now sadly gone)

If this was the original HG, I believe this was the area that saw several revisions...

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http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

Thanks for the feedback and ingenious ideas.

I will give it a try and report back.

Thanks
Mark

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91 300GD SWB with transplanted 87 OM603 turbo motor

A thought:
Would tightening down the 2 bolts that are at the very front inside of the head where the chain rides help at all? Or would I risk cracking the head?

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91 300GD SWB with transplanted 87 OM603 turbo motor

You would not be cracking the head, if the bolts are like most other engines, they are not large enough to cause problems.