345 Stalls at Low RPMs; Mystery Coolant Leak

[tmcscout]

Hi Scout crew. I've got a 79 Scout II Traveler with a 345 and automatic transmission. It's not my first International, but is my first Scout. I've got a couple of questions for the more experienced Scout owners.

1. The Scout will occasionally stall and quit running after trying to accelerate from a complete stop; however, it will start again with no problem. Plugs, wires, etc are all new and the timing is correct. Any ideas on what could cause this?

2. I've got a coolant leak that I can't diagnose. Small amounts of coolant collect on the back of the valley pan, but I can't figure out where the leak originates. I've changed the valley pan gasket, but that did not help. I thought maybe the thermostat bypass hose might be dripping slightly (in fact, I am not convinced it does not have a very slow drip), but that is on the other side of the motor. Anyone out there have a similar issue?

3. I'm in Western NC, not too far from Asheville. Can anyone recommend an experienced Scout mechanic out that way? If not there, how about Charlotte, NC?

Thanks very much.

[76 xlc]

1. Could be a faulty accelerator pump or power valve.

[Scott Hickman]

#1. As noted above.

#2. Could easily be one of the 'welch' plugs on the bottom side of the intake manifold. Did you replace them when the manifold was off for the valley pan gasket replacement?

#3. sometimes myself, but I usually only have time for my own vehicles.

[gravedigger]

The coolant leak could be coming from many different sources. When you had the intake off to replace the valley pan gasket did you look at the welch plugs that are on the bottom side of the intake and inspect them as the possible source of the leak?
The stall you are experiencing from a dead stop could just be a worn accelerator pump. You can diagnose this by removing the aircleaner, and while the engine is not running and the key in the off position by looking down the throat of the carburetor and depressing the throttle linkage and determining if the stream of fuel that jets out is steady and unbroken, meaning no gaps in the spray pattern. It should also be instantaneous as you push the throttle linkage.

[tmcscout]

Thanks very much for the info. I did not look at the welch plugs before, but will definitely check them out now. Also much appreciate the info on the accelerator pump.

I really appreciate the tips. I've been reading this page for a long time and am always impressed by how much you guys know about these old binders. Many thanks.

[Jay Tabor]

pressurize the cooling system.

get rid of the water in the gas/carb accelerator pump

[Feedforward]

I had a similar problem after I replaced the intake manifolds. Slight coolant leak and also a vacuum leak that caused backfire/stalling on acceleration off idle.

The problem was that when I replaced the intake manifolds I did not realize the ones I had taken out were the corteco composite type. I wasn't even aware these were made. I used normal steel intake manifold gaskets and ran into the problems described above.

When I switched back to the corteco, the radiator leak and vacuum leak were fixed. No leaks since, and nice acceleration off idle now. Maybe machining is a better solution, but I went with the low-buck option first. If that hadn't worked my next steps were going to require a lot more time an money.

In this case, my mistake was not looking more closely at what I was taking off the engine!

Since you mentioned replacing the valley pan gasket, I was thinking this migt be what happened.

[tmcscout]

Thanks guys. I'll work on it this weekend (I hope) and let you know what happens. Again, thanks for the help.

[Scott Hickman]

Another thing to keep in mind when installing an intake manifold on the IH SV-8 engine: Some of the attach bolt holes are open to either the intake plenum or the water jacket. Using a smidgen of sealant on the fastener threads (NOT RTV) is prudent to prevent vacuum leaks and/or coolant leaks in these areas. Also be sure the threads are clean and without crud from the prior build.

[Binder77]

Permatex Hylomar (magic blue goop) works really well for sealing bolts ... if you can find a tube. Just a dab on the threads will do the trick. It's also a great gasket dressing. Just put a thin coat on both sides of the gasket and it will fill any small asperities on the head/manifold gasket surfaces. Make sure you don't have any gobs of it protruding into the coolant or intake passages.