my boss and i are working on a 48 F1 p/u with a stock flathead v8 in it and we keep running into water pressure problems the engine originally had a problem with a leak at the head that was causing frothy water so he took it down for a complete rebuild. the engines back and installed yet we are still getting a lot of water out of the radiator overflow the radiator is one purchased from Sacramento vintage ford for the v8 flathead stock configuration. we noticed the original radiator has a "baffle/dip tube" at the neck/cap and the replacement does not we are not running thermostats and we have a 4psi cap installed and we are scratching our heads here any help would be appreciated Scott
Do you have pics of this baffle/dip tube? I would suggest running thermostats. I was running a 4lb cap as well, and getting some overrun, and my tank looked like it was ready to burst, so now I run it with the cap on only one click so it has zero pressure.
Try leaving the water level down a couple inches in the tank. Usually once they find their "level", they will stop puking.....otherwise you have a head gasket or other leak letting combustion gasses into the coolant.
I agree with RMR&C. I usually keep my coolant level at the bottom of the pipe - that's 2" - 3" below the cap. Without an expansion tank the coolant has to go somewhere and 5 gals of coolant will expand a bit. Just quit refilling it and let it reach it's own level.
I've built flatheads for years. If it is developing pressure inside, the best thing is to find out why. Take the truck to your nearest smog station, and with the engine idling, have the tech hold the sniffer over the open radiator neck. If there is Carbon Monoxide (c/o) leaking into the cooling system, it is chemically heating the coolant, not thermally. If c/o is found, now look for a head gasket, cracked block, etc. Let the truck sit all night, disconnect the coil wire, and crank the engine over about 5 revolutions. (8 seconds) Now remove the plugs, tapping the electrode end in your palm. If droplets of water appear, that is the cylinder where the water is. If not, pressurize the radiator at the neck with a hand pump. Crank the engine over with the plugs out. Leaky cylinder will pump water out the open spark plug hole. Hey, who's paying $5K for a flathead rebuild? I'd like to get some of that...
thanks for the replies..... will get back to everyone once we try some stuff we have a buddy a block away who does smog so we can give that a go
he knew there were a few hundred parts per million of carbon without even running the engine and the 7pound cap were trying is puking out the overflow but my point wont the stopleak work only if the problem is in the opposite direction.... i mean wont the stop leak seal from the water side and the exaust leak will just blow it out... and why would you put stop leak in a rebuilt engine with 10 or less miles on it?
Please trailer the truck back to the rebuilder, Scott. For that kind of bill, the c/o should stay where it belongs. For leverage, you may have to mention the Calif State Bureau of Automotive Repair, but let's hope not. Stop Leak NOT advised, the rebuilder might just use that as a "Well, you shouldn't have tampered..." Good luck. This is 'sticky'.
Have you retorqued the head bolts? Usually has to be done several times. Let the engine completely cool down before torquing. I did an engine for a fella with a 35 coupe. Same deal, kept puking water. He had bought a new aluminum radiator with a 7 lb cap. Couldn't keep water in it. About drove me nuts. Finally bolted one of my stock 36 radiators in and presto, no problem. The new radiator could not handle the flow. Sent it back. PS, sure wish I could get that for rebuilding an engine here in the midwest.
i would have better off flying as hamb'r out here from "back east" and having him do it.... i probly would have a running truck and a fuller wallet
This fella had someone else build the engine originally. Had the overheating problems and got a test kit which indicated exhaust gas in the coolant. Tore the engine apart as he was convinced he had a cracked block. Called me looking for a new block. I had him bring his over and I pressure tested it and it was absolutely sound, so I don't know if I would trust this test.
Exhaust gas in the cooling system does not necessarily mean a crack. Bad gasket ,porous casting head or block. And I remember recently on here someone had a block that had a exhaust bolt hole drilled to deep that let exhaust gas into the cooling system.
trying a compression test this morning and we charged up the cooling system up to 5 1/2 pounds and it dropped down to about 2 pounds in a little less then a hour
ok so im a little perplexed... i can pressureize the system at the radiator cap and the pressure wont drop at all overnight but when i run the system it builds pressure up and over 11pounds.... i hate to pull this motor again
Heat related issue ,motor warms crack whatever opens. Also combustion pressure is a hell of a lot more than whet a tester makes.
Scott, I'm going to try and revive this thread.... I'm having the same 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). 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 the leak test to see that there are no combusion gases in the coolant. 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.
Put the stats back in. You have to leave expansion room in the top tank,only fill the top tank about 1/2 way up.
Put the thermostats back in. They will slow down the water flow so the engine will cool better. What happens is the hot water around your cylinders don't have a chance to circulate because the flow is too fast. Sounds odd but it's true. If there are any combustion gases getting into the coolant, there should be bubbles coming up through the radiator. It is very obvious if this is the case.
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