VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc Coolant Leak From Below Front of Engine

After installing a new gas tank and fuel pump, took my 41 Chevy Special Deluxe out for a quick spin this morning (still clunky and needs a lot of suspension, brake and steering work... and the newly fixed horn started honking after a sharp left turn). Anyway, after parking her back in the garage, I noticed coolant leaking from somewhere under the front of the engine - an inline 216. I've already replaced the thermostat, housing gasket and water pump gasket. Looking down there with a flashlight, I can see it's not any of the hoses but cannot see where it's leaking from. Could it be coming from the bottom of the timing gear cover? If so, I assume that's going to necessitate removal of the radiator to gain access.

Sounds like it might be the water pump seal.

Using a flashlight, I can see all around the water pump and thermostat housing. It's not coming from there (just went out and verified). I know on some engines, the coolant circulates through the timing chain cover but I don't know about an inline 6 with a timing gear. Looks like it's below the crankshaft pulley wheel.

After taking a short run your finger under the water pump casting. There is a weep holed in the casting for coolant to drip out of when the seal goes bad. If you have plain water in the system it will evaporate, if coolant it will be easier to find as it does not evaporate as fast.
There is no coolant in the timing cover area.. just the water pump above it.

OK, so I feel like a doofus now.

Let it fast-idle for 10 minutes and then took it for a four-mile run to heat up the engine, parked it, and then quick checked under the hood. It's coming from the radiator overflow. Temp shows between 180 and 212 so it must be overheating. It runs from the overflow for less than a minute so I never noticed it was coming from there but, duh!

Already replaced the thermostat but shop manual mentions routine back flushings to clean out rust and crud. Anyone have experience with this or is it best to just buy a new radiator, even though it has no leaks?

An additional side-note on back-flush or replace. The car was sitting for over 12 years before I found her (on my birthday, so I guess it was meant to be). Just wondering if 12-years worth of rust can be back-flushed out or not.

Do a search on this site as there is lots of information regarding overheating.

Thanks! I usually do search the forums (and Google) for technical topics before posting but I was more looking for an opinion this time - is it worthwhile to back-flush a cooling system that's been sitting for over 12 years or just skip to the end and buy a new radiator? This after spending two days trying to refurbish a gas tank with POR-15 only to discover it had so many leaks that it was best to just replace it anyway.

The engine is over 70 years old and that s how long it has been collecting rust. Many engines from that time frame were filled with rust by the time they were 10 years old.
The rust from the block is plugging up the radiator.

If you fill the radiator to a level above about half the depth of the top tank coolant expansion can cause the issue you described. The temp going close to the 212 is a bit worrying though.
Tony

Yep, if I remember, the radiator was only half-full when I bought the car in January, which means it had been sitting that way for over 12 years. And, based on the cobble-job repairs I see throughout the car, I'm doubting the cooling system was maintained as outlined in the tech and owner's manuals.

I'm pretty sure the radiator isn't completely clogged because when I test drove it I turned the heater on and it blew hot air, meaning water must have been circulating through it.

Figure my best bet now is to clean and back-flush the radiator, block and heater core according to the tech manual - doesn't cost much and may just work. The car's a champ. When I first bought it, I thought the gas tank was empty and put 5 gals of gas in it. After a carb rebuild, new points, plugs, etc., I got the engine started. After I drove her home, I siphoned 10 horrible-smelling gals of gas out of it, meaning she was running on basically 50% turpentine. Now that's a hell of an engine!

Thanks to everyone for the suggestions and opinions! I've got her running and driving. Now I'm just working to make her run and drive better.

Check my posts on radiator, heating, flushing, etc.

I've posted them several times.

Charlie

Instead of using one of the modern-day flush kits, which purport to flush the entire system at once, I think I'll go with the tech manual method. First clean the cooling system and then back-flush each system separately - radiator, engine block and then heater core. Just seems to make more sense if you want to make sure everything's clean and clear.

Oh, and by the way, Charlie, I read your previous posts and realized one mistake I was making - filling the radiator all the way up. So it could just be the expansion that's causing it to run out the overflow but, as old as it is and as long as it was sitting, I figure a good cleaning and back-flushing can only help it.

BJ you are right, a good flush will not hurt as you suggested (each section separate) and I suggest using compressed air to help stir the rubbish up. Filling above half the top tank will result in a puddle after the first good run at full temp.
Tony

Yes, you should backflush each component separately. I did that when I was preparing my '37 to go back on the road. I do not have any indications of overheating even in stop and go traffic on a hot day.

I removed the radiator and took it to a shop to pressure test (use very low pressure, no more than 4 psi) and clean it. He also did the heater core. To remove the radiator I of course had to remove the water pump because the engine was still in the car. I also removed the thermostat housing and water outlet on the head.

I then made some simple adapters so I could flush the block multiple ways. I could flush by putting water into the head and let it come out either the water pump opening or the block drain. I could push water through the block drain and let it come out the front to the head or the water pump opening. Then I could push water into the block through the water pump opening and let it come out either the front of the head or the block drain.

Yes, it got a little messy and I got a little wet. It was a warm day so things dried quickly. It was amazing what came out!

Chev Nut, you were right. Cleaned the system and then back-flushed the radiator, block and heater core separately. The radiator ran clear almost immediately as did the heater core. The block though... Couldn't get much flow through it at first and then something "broke loose," a bunch of gunk came out, and the water flow doubled. Had to flush for almost a full minute before getting clean water.

Took her out for a spin after refilling and the temp averaged just under 180. Once it reached 180, I could tell that the thermostat opened because the temp dropped quickly to 175 or so (it's a 180 degree thermostat).

On a side note, I parked her up at the post office and, as unfinished as she is, she still attracted a small crowd!