2005 losing coolant after replacing cylinder head/ headgasket

I just put a refurbished cylinder head on my om647 using all factory procedures and new stretch bolts. After a month of so of use it's started to use 1 litre of coolant every hundred kilometres. Just pressurized the system to 18 pounds and ran the van can't find any leak. I have replaced the water pump and almost all the hoses. I am almost certain it's a cracked head. Any advice would be appreciated. The head still has warranty on it.

A compression leak at the HG is definitely possible. The head may not have been decked properly, etc.

Have you checked the front/sides of the engine for white deposits (like hard water build up). The coolant pump and other small hoses can leak slowly, and the fan just blows the coolant around, making it hard to see the leak source.

Thanks for the reply! I checked around the entire motor and I don't see any signs of leakage to support losing a litre of coolant every few hundred kilometres. Seems to lose more if I'm working the van harder up hills. The engine hot will hold twenty pounds of pressure which is more than enough I would think. When the engine is held at 2500 rpm hot I can observe a big bubble every 15 seconds or so coming out of the reservoir.

For the non-metric minds, this is leaking about 15 millilitres, roughly a TABLESPOON per minute. Hardly slow...

At that loss rate I’d expect to see a puddle under the van, to smell it in the exhaust, and/or see milky oil in the sump from blow-by,

Speculation: Your new head may be falling victim to whatever took out your old one... or it may not have been decked flat?

-dave

Edit: Overlapped your post. The 15 second bubbling is a bad sign, and I would begin a warranty claim soon.

Quite a significant loss indeed! No milky oil, no oil in coolant tranny fluid clean as well. I'm gonna bet the machine shop didn't know what they were doing. When I received the cylinder head the injector seats hadn't even been touched. Thanks for all your help I'll call then in the morning see why they say.

Reading the dimensional checks in the service manual, there is VERY little meat available on the head for resurfacing, or a valve job, before the component is scrap... an unfamiliar shop would quickly go past tolerance?

-dave

I would agree Dave combine that with very thin casting near injectors seats and it's a cracked waiting to happen. My last cylinder head was retired due to someone using a standard bolt to hold down the injector resulting in the system pressurizing and blowing out of the bottle. Guess I'm in for the second head gasket job on the same van!

If there’s no coolant in other sumps then there’s a (small?) chance the EGR jacket is perforated? I have no idea how you would go about testing for that...

Any perforation big enough to allow exhaust through at those pressures, would easily allow coolant to pass during a pressure test.

A HG leak would pass combustion quickly due to high pressure. But little coolant due to low pressure.

Put a catch bottle on the rad overflow, I bet that's where it's going.

Little update. Spoke to the shop who sold me the head and they can't produce any paperwork for how much was skimmed of the head. I was told the bare minimum was taken off but not how much. I'm getting a new radiator tomorrow to eliminate that as a possibility. I would just like my money back to buy a new head. Lesson learned on this one

This is easy to know.
Take a micrometer reading from the back of the head where it overlaps the block.
From that reading you can compare it to a standard new head stack height --conundrum solved !

Of course I was always taught to stamp the amount removed in rectification on a visible area to immediately inform the next repair operative what is/was the current rectification level.

All too easy!
Dennis

These long cylinder heads with iron blocks and AL heads are more sensitive to proper prep, and good machining practices. Lots of length, and plenty of expansion/bending forces to corrupt the head gasket.

Midwestdrifter said:

These long cylinder heads with iron blocks and AL heads are more sensitive to proper prep, and good machining practices. Lots of length, and plenty of expansion/bending forces to corrupt the head gasket.

Click to expand...

I always liked the compound heads on Penta engines, but makes it kinda hard to have an overhead cam...

Any updates on your issue?