Blown head gasket?

[Russco]

I have been fighting this for a while now and thought I had it fixed but it's still acting up on long trips. This weekend I drove about 2 1/2 hours (@ 60-65mph) with the temp about 190 then I smelled coolant being puked out the temp then dropped to about 180. I knew something was up, so I stopped at the next exit. The temp spikes to 240 I topped it off (11/2 gallons) and it was fine again for the next 100 miles to where I was headed. I've noticed if I run faster than about 65 it will do it and it always takes about the same 11/2 gallons to top it off. I can drive it around town for weeks and it won't get hot or purge Any coolant only on the highway and if I run faster it will do it sooner. It holds pressure when tested, doesn't smoke, runs fine , no oil contamination. What do you think? My other thought was that maybe the radiator is somewhat restricted could the pumps build enough pressure to force it out the cap ( the cap is new and correct length 7psi). Edit: I didn't mention this is a stock 8BA in a 51

[Henry/Kokomo]

I suspect that the system is overpressuring. The combination of pump force and high, sustained heat appear to be forcing coolant out the overflow. Also, just because the cap is new doesn't necesarily mean its good. FWIW

[Russco]

Thanks I'm pretty sure the cap is good it's the second new one I've tried they both made no change.

[Henry/Kokomo]

Have you had the cooling system checked for evidence of combustion gasses which would indicate a leaking head gasket?

[Russco]

No, thats a good idea I am going to check into that but the town I live in either won't have anyone that does it or it will cost an arm and a leg to check it

[alanwoodieman]

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fill the radiator full-up to the neck-crank the engine and watch for bubbles, sometimes you can see the combustion gases from a leaky headgasket. also pull the plugs and look for a "clean" electrode on a plug-water will clean the carbon off, easy checks. also another thing you can try is filling the radiator up-only after you have warmed up the engine to temp with no pressure cap and then put the cap on

[jdl]

there are two sizes of radiator filler neck depths on 49-51 Ford radiators, measure the depth of your radiator neck and compare to the depth of your cap, maybe it is the short cap and not seating in the radiator.

also it is easy to put the thermostats in upside down on a 8BA is the
arrow on the stats pointed toward the radiator? also sometimes those radiator caps with a lever don't seal real good. just a shot in the dark....

[jan bogert]

i run a 4lb. cap, and i have a stainless 20oz. overflow tank.

[OLD...BILL]

Ken: One more check, woodman came close, your rubber tip blow gun in the plug hole, one at a time, be ready for the piston to be pushed down, now check for bubbls in the water, hold a steady 40/60 lbs. and look and lisen, you will hear air going everywhere. I think the combustion gasses, is kit you can buy and do it your self. its something you put in rad, water and check for color change ?? OR you over filling the rad?? ....OLD....BILL

[jdl]

From a Ford service bulletin..

[jdl]

More on the subject...check the easy stuff first, please keep us posted

[alanwoodieman]

I can't believe I forgot the one about putting pressure thru the plugs for leak testing-I even did a 38 truck last summer that way-must be getting old!! Thanks Old Bill

[Russco]

Thanks guys, I have a leakdown tester I will try that too, but its odd it wont produce any bubbles at idle or even revving in nuetral. I've been fighting this for a long time been thru the cap deal,Had the radiator tanked and tested 3 times they swear its good. pressure tested the system it will hold 12psi and if its leaking I think its a very slight leak that happens under load at higher rpm's? is that possible? the wierd thing is that evevry time it does it it takes almost exactly the same to top it back off 1 1/2 gallons.

[wga]

I had similiar problems. Find a shop that will check for combustion gases in the coolant. May not show up at idle, drive it hard, then remove the cap and have the
exhaust gas sniffer ready to go. My 8BA were 80PPM. After new head gaskets, block sealed with Irontite, readings were 6-8 PPM. First find if you have exhaust gases in the coolant. Cost me a donuts and bagles for the shop, they enjoyed working on the flathead.

[G.M.]

Russco Are you sure the bottom end of the pressure cap is seating down on the washer like seat about 1" down in the neck. My bet is it isn't I have found 100s that did not seat. When you put the cap on align the the cap so you can push it down and you should feel the spring loaded rubber end hit washer seat and the spring action about 1/8th inch before the upper seat in the cap hits the top of the filler neck. I have used a 3/32 to 1/8" rubber washers the size of the seat on my cars because the caps are all to short. If it works clean the seat good and use a small amount of RTV to hold it in place. When done fill the radiator right up to the neck slowly as the engine warms up. A 4 lb cap is all you need. G.M.

[columbiA]

ON a 33 with a 59A I was loosing coolant.I removed the top rad hoses & T-stats,removed the WP belt & filled cooling system almost to the top of water necks on cyl heads.Ran engine at various speeds & noticed bubbles rising in one cyl head.Replaced the head gasket on that side & it was OK. It was nice not having to guess which side to change.

[49r]

I chased this one for a while with my 8BA. New rebuild, decked block and heads. Bubbles didn't always show in the radiator and would only blow out the overflow when I pushed it ... until the head gasket let go properly and I lost number 8. Out hosed the tell-tale water when I compression tested the cylinder. Put on another new composite gasket that was hanging on the wall (maker unknown but looked ok). Re-checked head torque after every run but 200 miles later same problem. Leak-down test identified the cylinder. Replaced head gasket with Fel-Pro and 200+ miles later I think (hope!) I've got it beat. Lesson for me - use top quality head gaskets and keep checking head torque after every run (cold) until there is no more movement.

[Russco]

Thanks I have a set of Graphtite gaskets here Ive already retorqued the heads,there were a few that were backed of a bit but it didnt change anything. Im going to try to find someone to do a sniffer test on it.

[JWL]

Just remove the upper radiator hoses and the waterpump belts. Fill both banks to the top of the thermostat housings, with water. Start engine and let it warm up for a couple of minutes. Now, with engine at idle speed, stab the throttle wide open, for about 2 seconds. while you observe the action of the water at the top of each thermostat housing. Do this several times until you are confident you either have a combustion gas leak, or you do not. The rapid movement of the throttle, to wide open position from idle, allows for maximum air pressure to enter the cylinders and will produce temporary internal cylinder pressure similar to the highway loads. If no leaks, we need to discuss the next step.

[Russco]

Ok so I tried the test described above, the left bank did push water out and showed some bubbles. (After a few minutes the right bank also pushed a little out but nowhwere near as much as the left bank) I think it may have been just water expansion it was getting upwards of 190-200 on the gauge by then. Anyways I bit the bullet and pulled the left head off.

I can't see anywhere it was leaking at all. I can't see any cracks even the usual bolt hole cracks are not visible. Here are a few pics maybe they are good enough to show something I am missing.

Edit: on the bright side I found it has a 4 inch stroke. (which explains why it pulls better than my 239 in my model a coupe)