Oil vs gas leak

[Roger G.]

This looks like oil and feels like oil but seems to be coming from the front and rear carbs on a 69 tripower. Here is a couple of photos of the front carb. Notice the pooling on top of the thermostat housing. Also on the carb just above the thermostat housing...any ideas what is leaking?

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[John C.]

Re: Oil vs gas leak

Rodger

You have a gas leak. Not unusual for a Holley carb. The heat of the intake manifold is evaporating the lighter parts of the gas leaving the heavier parts behind.

The major downside of Holley carbs is the vertical split seam and required gasket to seal between the gas bowl and body. Having three Holley's only compounds the problem. First thing I would do is make sure the four bowl attachment screws are tight. These can loosen from the heating up and cool down cycles the carbs go through.

If this doesn't solve the problem you probably have a warped bowl, body, or metering plate mating surface. If these are not flat it is easy to get a gas leak at the vertical seam.

If it is the center carb you should also check for leaks at the accelerator pump gasket on the bottom of the fuel bowl.

On any car equipped with a Holley I always start the car and check for gas leaks before taking it out for a drive.

John

[Terry M.]

[Roger G.]

Re: Oil vs gas leak

Thanks for the info guys. It does smell like gas in the garage after coming back from a drive. That stuff was so thick and dark, it really looked and felt like oil

[William F.]

Re: Oil vs gas leak

Do you know if carb has original type paper gaskets or the newer blue reusable ones. Newer ones won't "judge" but they do a much better job of sealing. Get some made by Holley- and torque to 30 in. lbs and problem ay be solves without worring about warped parts, etc.

[Stuart F.]

Re: Oil vs gas leak

I am presently rebuilding my son's 69 tri-power Holley carbs. I haven't touched a Holley for about 30 years (on purpose cause I hate them). I started with the center carb first. These carbs were last rebuilt back in about 2000, and the gaskets are baked on. I've had to work real hard with a scraper, but I don't know how to pop the float chamber loose without damaging it (like in a vice). Anyone have any ideas?? The reason I have to rebuild these carbs is due to leaks also. No matter how good the gaskets and O-Rings are if the fuel percolates it will find a way out to spill/collect on the intake manifold. These are from an L-89 with aluminum heads as well as intake manifold.

Stu Fox

[Domenic T.]

Re: Oil vs gas leak

Terry& stu,
Well said I thought I was the only one that didn't like Holley carbs, reasons that I will not say, but I have to live with my tri power. Took the 4 brl off my driver and adapted it to the dime a dozen Q-jet and get better perfect & milage.

DOM

[Mike T.]

Re: Oil vs gas leak

Stuart - Once all the screws are backed off, I usually try a putty knife or a screwdriver but that can also ding and dent the bowl so I use a soft mallet and try to 'gently' persuade the bowl free with a few light hits from either side. So far, I haven't damaged any Holley Fuel Bowls (knock on wood, fingers crossed, etc ;-).

[Stuart F.]

Re: Oil vs gas leak

Thanks for the advice Mike. I'll give it a try. Here in Florida it's already hot so I can only work in the morning out in the garage, so I'll get back at it again tomorrow. Time now for my nap, Ha!

Stu Fox

[Jim T.]

Re: Oil vs gas leak

Do you know if carb has original type paper gaskets or the newer blue reusable ones. Newer ones won't "judge" but they do a much better job of sealing. Get some made by Holley- and torque to 30 in. lbs and problem ay be solves without worring about warped parts, etc.

William I really like using the Holley blue crab gaskets, and I can attest they are reusable.

[Stuart F.]

Re: Oil vs gas leak

Michael T.
I got the bowl off easy with a wide putty knife all right. The metering block is a little more stubborn. It is easy to see why these carbs have trouble with the ethanol tainted gas. I found one main jet completely plugged, and a great deal of white scale/deposits. Now I understand why the four long screws look corroded on the threads, almost like from moisture. These carbs were on the car and functioning barely a month ago, but not well. The power valve is stuck as well. Now I recall why I dislike these units so much.

Stu Fox

[Mike T.]

Re: Oil vs gas leak

Stuart - I guess I'm lucky that I haven't had to deal with the Ethanol issue when I lived in Northern California or now that I'm in Arizona. But since those carbs you're dealing with haven't been touched since 2000, a good cleaning and rebuild should be good for another 14 years...we hope. Any tank rust debris showing up or is it strictly old fuel varnish that you're finding? As has been suggested already, those Holley Blue gaskets do work well but will have to be ordered separately because I don't think they come in any rebuild kits.

[Stuart F.]

Re: Oil vs gas leak

Mike T. - I got the metering block off with some effort using the wide putty knife driven in at least on 3 sides, then prying off with s scraper. WOW! What a job. I had forgotten they use a full surface flat gasket, and not just one with sealing surface around the perimeter. I'm glad I bought a set of small scraping tools this last January at our regional winter meet here. They made a quick job of gasket clean up. I found every screw and adjustment nut to be quite loose, and there were signs of gas migration through parts of the gasket (port to port internally). The white or off yellow crud had plugged up a number of holes besides the jet. I find it hard to believe this carb was ever apart since new, but I guess it was. Any idea how I can clean the black out of the venturies? I'd say this baby barfed up a few times testing the flame arrester.

Stu Fox

[Domenic T.]

Re: Oil vs gas leak

Stu,
Hope this in not a duplicate post because I couldn't find the other, but I use Berrymans to get the black out. A good soak is all it takes for us.

DOM

[Stuart F.]

Re: Oil vs gas leak

Dom- Thanks. Guess I was discussing the same thing on two threads. Sorry if I confused any one. I'm looking forward to getting some "Berryman's" tomorrow and getting this center carb cleaned up. The end units should be a lot easier. Some one mentioned using Holley "Blue gaskets". Do you know what advantage there is to them? I've heard that they might seal better on metering blocks that might be slightly warped. Is that it?

Stu Fox