Truck overheating help!!
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Truck overheating help!!
I'm new to this forum but I used previous posts to attempt a repair on my father in laws 84 F150... he overheated the 4.9 and blew the head gasket. I took it off, cleaned it up and installed the new gasket with copper spray sealer. Torqued the head down according to the specs I've read here in the forums. I adjusted the rockers using the zero lash method with the respective cylinders at TDC. Put it all back together and took it for a ride around the block. By the time I got back it was boiling into the overflow. Before doing the head gasket I replaced the thermostat and water pump I don't know what I did wrong... is it possible for cast iron heads to warp? It doesn't look like it's totally flush near the center of the head but with the rough casting it's difficult to tell for sure. So before I tear it back apart I figured I'd offer it up to some people who may have more knowledge on the subject. Any assistance would be greatly appreciated. Thanks in advance.
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Joined: Jan 2001
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From: Virginia
It is very possible for cast iron heads to warp and to crack also. I would take it back off and put a straight edge on it.
Also get some brake cleaner after you get it off and spray it down. Let it dry and look it over carefully. The brake cleaner will turn the oily surface a dark brown color. If you see any mysterious black lines, those are most likely cracks.
Also get some brake cleaner after you get it off and spray it down. Let it dry and look it over carefully. The brake cleaner will turn the oily surface a dark brown color. If you see any mysterious black lines, those are most likely cracks.
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Joined: Apr 2011
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From: Orlando area
Modern head gaskets don't generally need any additional sealers. Unless the gasket is not-coated from manufacturer (solid steel) your better off not putting anything on it.
Is it possible the radiator is just clogged up. Could the original overheating problem been the reason the head gasket went - if so, and you don't correct the original problem you're going to keep having problems.
Before pulling the head again, check everything else. It may be the new head gasket is sealing fine. Did you road test the truck after replacing the water pump and thermostat to make sure it was working properly - or was that replaced at the same time as the head gasket?
There is a tester to see if your getting combustion gases in the cooling system (from blown head gasket of cracked block/head). I don't know if you can rent this from the local auto parts store - but it's not too expensive if you want to buy one https://www.walmart.com/ip/Lisle-Com...&wl13=&veh=sem
Is it possible the radiator is just clogged up. Could the original overheating problem been the reason the head gasket went - if so, and you don't correct the original problem you're going to keep having problems.
Before pulling the head again, check everything else. It may be the new head gasket is sealing fine. Did you road test the truck after replacing the water pump and thermostat to make sure it was working properly - or was that replaced at the same time as the head gasket?
There is a tester to see if your getting combustion gases in the cooling system (from blown head gasket of cracked block/head). I don't know if you can rent this from the local auto parts store - but it's not too expensive if you want to buy one https://www.walmart.com/ip/Lisle-Com...&wl13=&veh=sem
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Well, I know why it blew, it's because my father in law is almost 70 and doesn't quite remember things right all the time. The radiator had a leak and he was adding fluid until he had the scratch to buy a new one. Well somehow he got it in his head that leaving the cap halfway open would make it run cooler...�� So he filled it and went down the road to take care of some things, viola! It wasn't smoking or anything so once I got it back to the house I was hoping he hadn't destroyed it but once the water pump was replaced we fired it up and there was the smoke and the rough running... that's when I pulled the head and found a ton of water in the cylinders... I'll look into that leak tester. I sure wish he had ran that awesome solution by me first.
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Joined: Nov 2015
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From: Angier, NC
The cap half on or not at all is not such a bad thing if you know why & when to do it.
If it is on all the way the system builds up PSI. Because the system has a higher PSI than outside it the boiling point is higher than 212*f. That is the only reason I know of the pressurized cap.
Even if it is the lower radiator hose. A little tape over the hole, fill the system, cap on half way and away we go to get a new hose. If the system was to build PSI it would blow the tape off the hole.
Dave ----
If it is on all the way the system builds up PSI. Because the system has a higher PSI than outside it the boiling point is higher than 212*f. That is the only reason I know of the pressurized cap.
Even if it is the lower radiator hose. A little tape over the hole, fill the system, cap on half way and away we go to get a new hose. If the system was to build PSI it would blow the tape off the hole.
Dave ----
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Joined: Jun 2013
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From: Somewhere n North America
Sounds like the empty radiator was the cause. Hopefully the rad was fixed or replaced.
I would have the head minimally shaved myself.
Water in the cylinders again?
Thermostat installed in the right direction?
Fan working properly?
I would have the head minimally shaved myself.
Water in the cylinders again?
Thermostat installed in the right direction?
Fan working properly?
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