Flathead motor spewing coolant, but not overheating....

[phartman]

I'm having a problem with my '34. 21-stud motor. Motor rebuilt by a reputable shop about 6,000 miles ago.No thermostats, treated distilled water. Engine runs 160-180 degrees, but will puke water when it is as low as 140. Rev related. Will only puke at the top end of the rev scale, under load.

The guys at The Pit Stop in Texas suggested that there was something (sand, gunk, crud) moving around in the cooling passage(s) and blocking a passage. He reckoned that the blocked passage was preventing coolant from circulating, until it got hot enough from the steam that it blew coolant back through the system and out the cap.

I had Skip in Florida rebuild the water pumps and I replaced the original radiator at the same time. Prior to these two changes I had zero problems. Approximately 25 miles after replacing the pumps and adding the radiator, the system puked. I believe that due to the better efficiency of the pumps, the original aluminum heads shed quite a bit of scale and electrolosis gunk. Reverse flushed the system and quite a bit of scale came out.

Changed the aluminum heads to newly machined cast iron heads. Used the graphite head gaskets, retorqued after the heat/cooling cycle to 50lbs. Motor ran great for maybe 35 or 40 miles or so, and then today, puked coolant.

I will run a leak test to see that there are no combusion gases in the coolant due to a cracked block. However, the puking issue seems to be rev related on the coolant side. My thought is that if there were a crack, it would have shown up before I replaced the radiator and had the pumps rebuilt.

Ideas? I keep thinking that there is something moving around in the motor, coolant wise. Or maybe the radiator can't handle the flow from the newly rebuild pumps. Put the thermostats back in the motor? I'm open to other ideas. Very puzzled right now.

Thanks for your help here.

[Dave72dt]

The scale may have partially plugged the replacement radiator. Put the original back in and try it that way or the thermostats. You've made at least 3 changes to the cooling system and you'll need to eliminate the variables one at a time.

[flatjack9]

I would bet that the new pumps (which pump more water) are overloading the radiator. Did you replace the radiator with another original type radiator?

[phartman]

flatjack, no, I did not use an original type. Well, I take that back...the Griffin design is to '34 Ford specs. However....we noticed that the original has a baffle in the top of the radiator and the Griffin does not. The original Ford has a plate, if you will, immediately beneath the cap opening. A baffle that deflects water returning from the top inlets. The Griffin does not. With the Griffin you more or less see further down into the top chamber of the radiator. It does have an overflow tube, but it is at the top of the chamber immediately underneath the radiator cap. The original Ford design was the overflow tube to the side, on top of the baffle at the top of the chamber.

So I was wondering if these newly rebuilt water pumps at top rpm are moving so much water that the overflow tube at the top of the radiator is not enough to handle the flow. The water finds the path of least resistance and spews out the cap. Dunno.

It is an intermittent problem, but it definitely only occurs under full power at the top of the rpm range.

And, again, the engine temp gauge is running 160-180 degrees.

Design flaw in the radiator??? Solution? Tomorrow we were going to run the leak test. Then try termostats or flow inhibitors. We had in mind using the 160 degree tractor units.

And, again, many thanks for your help here.

[cmbrucew]

Try putting the thremostats back in.

[Brendan]

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i had that trouble in my 35 21 stud motor, i put freeze plugs in the water pumps and drilled a 5/8 inch hole in them it seems to like the change. now the water is just to the top of the baffle right at the little hole
Brendan

[phartman]

Yes, Brendan, thanks for reminding me. While the truck is a '34, the motor is a 21-stud '36 with insert mains, cam bearings and adjustable lifters. I have receipts from the rebuild. Quality parts. And the distributor was converted to the later style by The Pit Stop fellows in Texas. I'm running the Stromberg 48 carb, Fenton headers and otherwise stock motor.

[Mike in AZ]

perhaps after it pukes out coolant, don't add any back??....if it still runs cool and doesn't puke any more out, run it like it....good luck....Mike

[JWL]

Is there a pressure cap on the new radiator? I don't see any puking to be possible with a pressure cap unless the cap does not fit or the engine is hot or there is combustion pressure getting into the system.

[Walt Dupont--Me.]

If the cap is tight the water is going out the overflow. The pumps do pump more volume and blows the water out the over flow. Ship has a 3# pressure valve that goes on the end of the overflow pipe. That will fix your problem. I had the same problem with my Model A with a warmed up B engine, I was always adding water, installed the pressure valve and never add water. Walt

[OhioRick]

Yes,
Skip always recommends adding the 3 pound overflow valve at the drain hose. The old style radiators have a design that has the overflow hose above the radiator cap seal. The Overflow will still throw out coolant. Unless your newer radiator has the neck design that also controls the overflow.
Your coolant height is normally lower than what you'd expect it to be. You have to leave room for expansion or you could damage your pressurized radiator. If you will be using the 3 pound valve, a cap should be close to the same pressure.

[chuck stevens]

There's a chance that under high load and rpms the head gaskets are leaking compression into the cooling system. I have an 8BA bored to 3 3/8 that has this habit, on long hills and full throttle, just a thought, Chuck.

[phartman]

JWL, Walt, I believe that this system is unpressurized, or at least runs with very little under load. The cap is the stock radiator cover with a new gasket. And there is no external expansion tank. It could be- just could be- that the water is going out the overflow hose until the volume reaches a point that the hose diameter can't handle it. The water seeks another exit and the cap is the point of least resistance. After it pukes out the radiator cap, we did check and the overflow hose was wet, so some water is coming out that way. I can't tell how much.

We've been filling the radiator to the top of the upper tank so that you can just barely see water, but that still may be too much. After it blows, I've had to add back maybe a gallon or so. Too much coolant in the radiator is causing the problem?

Again, the coolant temp has never, ever gotten over 190 degrees or so. And, yes, it wants to puke at high rpms or on a long pull up a hill. Last time it did it, I was at the end of the acceleration lane getting onto the Interstate.

The overwhelming recommendation is to put the thermostats back in and slow down the flow of the coolant. I guess ol' Henry's engineers in 1933 figured that out, too.

[Chris Marshall]

Originally Posted by chuck stevens

There's a chance that under high load and rpms the head gaskets are leaking compression into the cooling system. I have an 8BA bored to 3 3/8 that has this habit, on long hills and full throttle, just a thought, Chuck.

I think Chuck hit the nail on the head. I've had the same problem in the past. I built an 8BA bored to 3 5/16, merc crank, etc. Never ran hot, but when you really got on it at high revs, or on long runs around 70 mph (again semi hi revs) it would suddenly puke antifreeze out the overflow. Had a pressurized system with a 7 lb cap. I fought this for several months. Looked into water pumps, thermostats, etc. Finally pulled the heads and found evidence of compression leaks on both sides between the rear cylinder and water passage. This was using copper head gaskets. Went to Best composite gaskets and cured the problem.

This engine is in my T-V8 roadster. My wife really hated the sudden green "showers"

[37don]

If you have an original top tank the overflow is below the cap seal so the Skips 3lb valve is all you need as was posted above. A pressure cap won,t help at all, you need a good gasket on the radiator cap. I have a freind with a nice original 36 and he said he tried everything without any luck. Put on the Skip valve and problem gone.
Good luck, Don

[Fibber Mcgee]

I had the same problem as you.Trust me put the thermostats back in.I put new pumps and it started spraying water out overflow same as you,as soon as I put in tstats it quit.

[FRANK PKNY]

You can buy a kit to test for exhaust gas in the cooling system. It's about $35.00 works perfect . Then you will know if you have a block or head leak and go from there. Frank pkny

[phartman]

Frank, yup, we're going to run that test first. At least eliminate that as a possibility.

Trying to find thermostats for the '34-'36 Fords. Tried Joe Smith Early Ford and Mac's. Neither has them. The tractor application will work, but the size is too small for the hose. Other sources? Other places that might have the thermostats?

Also, the '36 LB run such low oil pressure...I wonder if I'm better off with the 140 degree thermostat or the 160 degree. Any opinions?

And, fellas, again, many, many thanks. Yesterday my buddy Warren and I were wondering where to go to get guidance on this sort of motor problem. Hands down, Fordbarn has come to the recue.

[FRANK PKNY]

phartman, Can't help you with the thermostat's . But I would recomend talking to skip about the flow rate Possibly need just a plain restrictor plate? Do the exhaust gas test first. Then call Skip. Frank

[BrianCT]

I also have Skip's pumps in a 21 stud and had much the same problem when I removed the 'stats. Put them back in.