Coolant leak on W2 heads

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cpearce

cpearce

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Due to poor weather the last month and landscaping work around home my Dart has not turned a wheel in over a month and a half.

Recently I noticed a small spot under car on passenger side, it was coolant, enough to make a spot 2"x2" over 2 days. I crawled under and found coolant leaking down from exhaust flange area, and head to block around cylinder 8. I wiped it all and cleaned thoroughly and monitored. Dry for several days, then randomly wet at bottom of head again although not enough to drip.

I haven't had a chance to really dig into yet but I did pull rear most header bolt and it is dry. This has me stumped, the car has been on road 2 years with no leaks, engine was dynoed 3 years ago. Why random leak now? As I said car has not moved or even been started in month and a half.

I plan to loosen header and check there although I dont recal W2 heads having wet holes like standard LA. Perhaps the unused set of exhaust bolt holes are leaking???? Surely a head gasket doesnt randomly start leaking???? The weather has been very cool and damp, car is in garage. I'm considering firing it up and seeing if a few heat cycles will stop the issue. The coolant is Evan's.

Thoughts.........
 
I have read on here that some of the W2 heads were prone to develop a leak at the casting parting line on the exhaust side, but I don't recall the casting no.s that were suspect for problems.
 
My heads are the 65cc closed chamber P5249769 heads.
 
I'd make sure there's no coolant in the cylinder before I fired it up. 65'
 
If they are ECONO W2 heads the outer holes are very close to the water jacket. Just make sure you DO NOT have coolant in the cylinder and start it up. If you running headers on the inner holes you may see the leak on the outer exhaust hole. I have blocked them with an allen head set screw so it is deep enough to clear the header.
 
Have you re torqued the heads at anytime?
 
Only 1 pattern on my race versions... I have to look up the part #

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Mine were the Econo heads and they cracked right by the W2 casting on the ex side of each head. That really soured me on the W2 heads so I sold all my spare parts.
 
There were so many different versions.
Its hard to keep them straight.
It would be nice to have a list of all PNs and specs.
 
cpearce said:
The leak is above cylinder 8
Click to expand...


So the leak is below the port and above the bolt holes?? I made a phone call to find a notebook and look up the heads like that I've seen broken. Hopefully in an hour or so, she will call me back and my notes can refresh my memory.
 
yellow rose said:
So the leak is below the port and above the bolt holes?? I made a phone call to find a notebook and look up the heads like that I've seen broken. Hopefully in an hour or so, she will call me back and my notes can refresh my memory.
Click to expand...
Thanks for looking into. The leak is at block to head interface at cylinder 8. Is dry around exhaust port. I loosened header away from block, no moisture there.
 
cpearce said:
Thanks for looking into. The leak is at block to head interface at cylinder 8. Is dry around exhaust port. I loosened header away from block, no moisture there.
Click to expand...


I just got off the phone. My notes said we were finding broken heads because evidently, some of those heads didn't have the dowel hole drilled deep enough. That dowel pin would hold the head off the deck and crack the head under the port above the bolt holes.

If you have a leak between the head and the block and the head isn't cracked, you may have a dowel that is just a skosh long and is holding that end of the head up enough for a leak and not fracture the casting.

I knew there was a reason we were seeing those heads fracture.

Hope this gives you something to look at.
 
Dowel pin! So simple but yet so easy to miss. I’m still thinking of a possible re torque of the head. It’s possible!

Best of luck.
 
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