[Nitebird]

I have been trying to find where a coolant leak is coming from on my 1979 Trans Am SE. At this time I have a Pontiac 455 in it with Edelbrock Aluminum heads,TRW flat tops at 10.1 comp,RPM intake and Holley 950HP carb with Old faithful hydraulic roller cam. It has a BW Super T10 4speed. The engine and trans are both completely rebuilt and have about 15 miles on them.

When the car is running I can see coolant leaking underneath the car like its coming down from inside the driver side of the bellhousing starter mount area and then leaking down onto the ground forming a puddle underneath where the bellhousing meets the block area. There is also coolant on top near the distributor area and some on top of the very rear lip of the lifter valley tray.

I thought it was the heater hose that goes to the nipple on the passenger side cylinder head so last night I drained some coolant and reinstalled the nipple to make sure it was good and tight. But when I took it for a test drive today the leak is still there and in the same places.

I changed my oil yesterday to make sure everything is good and it was. There was no water in the oil or anything like that. It was clean and the magnetic drain plug barely showed anything on it. The car does not smoke and seems to run good but I need to find where the coolant is coming from.

Any tips on what it could be?

[mgarblik]

Of course with coolant leaks you have lots of possibilities. If you have access to a radiator pressure tester or can borrow one, you will probably find the leak rather quickly. Based on your description of the leak area, if you can remove the bellhousing cover, you might want to look at the two rear core plugs at the back of the block. You can probably see them with a good light and that cover removed. Again a pressure tester will save you lots of time. Let us know what you find. I just noticed from your post you have Edelbrock heads. Every now and then I have seen one or more of the accessory mounting holes in the end of the heads leak a little coolant from a tap breakthrough. Again with a pressure tester this will be very evident. Look at those holes with a mirror if necessary to make sure one isn't leaking. If it is, this is easily fixed with a set screw coated with pipe sealant with Teflon.

[fiedlerh]

Harbor Freight sells a radiator pressure tester for $90 and 25% coupons are abundant. I found if you put a thin coat of grease on the coolant fittings, it will stop those little leaks.

[Blued and Painted]

What head bolts did you use. Some have had problems with head bolts too long.

[Nitebird]

Originally Posted by Blued and Painted

What head bolts did you use. Some have had problems with head bolts too long.

If it were the head bolts wouldn't that cause coolant to get into one or more of the cylinders and cause a smoking condition out of the exhaust?

[Nitebird]

Originally Posted by fiedlerh

Harbor Freight sells a radiator pressure tester for $90 and 25% coupons are abundant. I found if you put a thin coat of grease on the coolant fittings, it will stop those little leaks.

That sounds like a good way to find the leak. I wonder how much pressure I will have to use at the radiator cap?

[form74]

Advance or autozone has rental testers for free , just need to leave a refundable deposit

[chuckies76ta]

Check the ones on the side of the block also. Coolant tends to run down different areas as the block is tilted downward some. There should be signs of staining on the block.

Charles

[Nitebird]

Originally Posted by chuckies76ta

Check the ones on the side of the block also. Coolant tends to run down different areas as the block is tilted downward some. There should be signs of staining on the block.

Charles

Yes there are in the areas that I had listed earlier and small puddling on top of rear of the block near distributor.

[chuckies76ta]

You can always put a dye in Rad and use an ultraviolet light to locate leak.. Also, if you have any leaks by Distributor, it would have to be the heater hose nipples at the back of the heads, or the lines coming off them.

Charles

[Schurkey]

Originally Posted by Nitebird

That sounds like a good way to find the leak. I wonder how much pressure I will have to use at the radiator cap?

What is the pressure rating of your cap? Something like 16 psi into the filler neck would not be out-of-line.

[Nitebird]

Originally Posted by chuckies76ta

You can always put a dye in Rad and use an ultraviolet light to locate leak.. Also, if you have any leaks by Distributor, it would have to be the heater hose nipples at the back of the heads, or the lines coming off them.

Charles

Yep that's what I thought also but they are tight and not leaking either. I have triple checked them and they are dry.

[82gplj455]

What about the seal between intake and timing cover.that will drip onto the valley pan and run to the back of the motor

[steve25]

Have you re-torqued your head bolts yet?
You have 3 different length head bolts, if they use washers under them remove one of each length bolt and make sure that they will bottom out on the head with the washer removed.

[track73]

I had a 400 Chevy that leaked at the freeze plugs on the side of the block. I forgot to RTV them before installation.

[indymanjoe]

Yellow shooting glass's and a UV or Black light will make coolant "Glow".I have found lots of leaks doing this.

[gtofreek]

Originally Posted by Nitebird

If it were the head bolts wouldn't that cause coolant to get into one or more of the cylinders and cause a smoking condition out of the exhaust?

Blued and Painted had a good point. If the bolts are too long[which has been the case with ARP bolts] then you won't be clamping the head gasket as tight as you should be. The sealing rings of the head gasket, around the cylinders, are the thickest part of the gasket, therefore, they will seal there first, preventing sealant from leaking into cylinder, but not to the outside of the head.

[Lee]

Are you using 1016 Fel-Pro head gaskets, by chance?