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right side coolant leak  Rating:  Rating
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 Posted: 05-19-2006 10:35 pm
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andrewo
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I have a coolant leak that appears to be coming from somewhere around the starter or dipstick. I have looked at all the likely suspects at the top of the engine, and none of them are leaking. I also placed towels above this area to catch anything that might be flowing down, and they are dry.

Any ideas what could be leaking toward the bottom of the block on that side? It does not leak until it is pressurized, either with a tester or by running.

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 Posted: 05-19-2006 11:25 pm
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Jim Ketcham
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If you have eliminated the usual coolant connections and the intake manifold and freeze plugs, then you might want to check head gasket.  It is not  uncommon for an external head gasket leak with the 907.  Good luck.

Jim

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 Posted: 05-20-2006 12:57 am
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andrewo
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I take it the freeze plug is the big threaded thing roughly between the starter and the distributor? Where do I get an allen wrench big enough to pull it out and reseal it?

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 Posted: 05-20-2006 05:20 am
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Mark Rosenbaum
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No, that plug seals the main oil gallery and has nothing to do with the cooling system.

For a definition of freeze plugs, see: http://autorepair.about.com/cs/generalinfo/l/bldef_233.htm

I've attached a photo of freeze plugs used for a different application.  The ones in a JH engine are similar.

Attachment: freeze plugs.jpg (Downloaded 135 times)

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 Posted: 05-23-2006 11:47 pm
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andrewo
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Okay, I have taken another look, and there do not seem to be any freeze plugs in the block, at least on the side of the engine that is leaking. I have a spare motor that I pulled the oil pump/auxiliary assembly and the motor mount off of, and I don't see any. What am I missing here?

The leak appears to be coming from somewhere below the head gasket. I can't figure out where else there would be coolant.

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 Posted: 05-24-2006 12:29 am
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Mark Rosenbaum
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What I can think of at the moment:
  • Pinhole leak in radiator core, coolant is being sucked back by fan and settles on engine.
  • Water pump or thermostat housing leak, with coolant being blown back by fan, or running down on front then rearward and down.
  • Head gasket coolant leak, possibly at rear, running down rear of block then forward and down; or at front, running down then rearward and down.
  • Hose from water pump to intake manifold leaking at either or both ends.
  • Leaking temperature sensor.
  • Leaking heater hose at intake manifold or heater core inlet pipe.
  • Block or intake manifold internally corroded to point of leaking through casting walls.
I've seen most of the above on various cars over the years.  The smaller the leak, the harder it is to find.  Sometimes a few sheets of newspaper, manually positioned near various suspect areas, can intercept a spray or other leak and give you a good idea of where to look.  Other times, you just have to cover the entire engine with clean white rags (e.g. bits of old tee-shirt) and see which ones get wet first.

Last edited on 05-24-2006 12:31 am by Mark Rosenbaum

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 Posted: 05-25-2006 03:32 am
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andrewo
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Thanks for the help. I have narrowed it down, and it looks like the head gasket. Aside from pulling off the cam towers and retorqueing the head, is there anything I should be doing or looking for? The head gasket is brand new. The engine has not even been broken in yet. It is the new style black one from Delta.

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 Posted: 05-25-2006 03:43 am
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Mark Rosenbaum
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If you're very lucky, retorquing the head nuts will work.  If you can test for leaks afterward without having to reassemble things, that's the approach to take.  If not, then I'd consider pulling the head and finding out why the leak exists (warped block or head, excess liner nip, or whatever), then eliminating the problem.

Just for information, in the unlikely circumstance that you didn't know, head gaskets can not be re-used.

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 Posted: 05-25-2006 03:44 am
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Jim Ketcham
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If the leak is minor you can try "stop leak".  I would only try the non-metalic type.  I had the same problem after a new rebuild and ultimately had to replace the head gasket and use the Lotus service fix of putting a very very small bead of high temp (red) silicone sealant on the new gasket.  That actually works quite well assuming you have the correct cylinder liner nip and good mating surfaces.

You will notice that on the Delta gasket the silicone  bead is only on one side as compared to the Goetz gasket used by Lotus.  

Good luck

Jim

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 Posted: 05-25-2006 03:50 am
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andrewo
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The leak is actually pretty bad. Since the Delta gasket only has the silicone on one side, which side do you recommend I put up? Also, what is the correct nip, and easiest way to measure it?

Last edited on 05-25-2006 03:57 am by andrewo

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 Posted: 05-30-2006 10:58 pm
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andrewo
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Just to close this one out. After convincing myself that it was the head gasket and having all the parts overnighted to me so that I could work on it over the holiday weekend, I went back to triple check and discovered that it was in fact the intake manifold gasket.

Of course, I had not ordered that gasket, but I was able to make one out of paper gasket material using the old one as a template. Of more interest was the fact that the casting was in pretty bad shape, so in addition to the gasket I used non-hardening Permatex Form-a-Gasket pretty liberally. Using a coolant system pressure tester, it does not leak down AT ALL.

Now on to the cam cover gasket leaks. I am probably going to resort to RTV for those.

Thanks again to everyone who chimed in with suggestions.

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