Coolant Leak

[rallyvan]

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I was filling the cooling system on my van today and was greeted by a pool of coolant around one of the intake manifold bolts near the #1 cylinder. It's been years since I have built a Holden V8 motor. I have thought of 4 possible causes this evening.

1/ My memory tells me that you had to used a special Holden stud sealant or a similar product on the head bolts but I can not remember if the intake manifold bolts need the same sealant or not. When I spoke to my mate who built the engine tonight he said he did not use any stud sealant on the intake bolts.

2/ There is a crack(porosity) in the cooling passage of the intake manifold. I had to get a new block(VN 304 block) as the 1st one was scored and at 60 thou already, new heads (the original heads where found to be cracked when the machinist pressure tested them) I would not be surprised if the intake is read for the bin as well. My mate who built the motor did not have the intake pressure tested it was just sandblasted and sealing faces checked before being installed.

3/ Head gasket issue of some sort

4/ There is a compatibility issue with the late model bottom end (VN 304) and the early model red heads.

Any ideas people?

[HK1837]

$1 is for head bolts as you say. I'd be putting money on the front water passage, either gasket, corrosion into the bolt passage (or both) or warping. Was the block or heads machined much?

[Big Rob]

For the coolant to be where it is, I would think its had to come out from around the manifold bolts, which means the manifold is not sealing correctly around the front water crossover. It could be leaking around the thermostat housing too, although it appears from the pic that it has enough sealant.

Try torqueing the bolts down a bit tighter before you tear it apart.

I always use sealant on manifold bolts in that area.

Don't panic yet..... try the easy fixes.

Oh yeah.... check the radiator hose clamp too.

[Vombil]

hmmmm ive had pools like that from a thermostat thats not sealing. other most likely is corrosion in intake or not sealing.

[Beachy]

You should do pressure test on the cooling system do it when engine is cold then do it at running temperature

[Kiwivan]

Had that problem,Remove the bolts,clean them up and use a sealant on the threads.
I would almost but the ducks nuts on this!!

Cheers Kiwivan
ps also check you have the correct pressure cap

[rallyvan]

Thanks for the ideas. I think I'll pull the bolts around the cooling passages and apply the sealant and see what happens. I haven't even started the motor so the cooling system has no had pressure applied as yet. Fingers crossed the sealing allows me to get the motor started and the cam run in! I think the long term solution is to hunt down a new manifold that is in decent condition and fit that up.