Blown head gasket
Thread Starter
Joined: Mar 2014
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From: Alamogordo, NM
Blown head gasket Have a 2003 LM4 in my '39 Chevy. Had to do a valve job, used new OEM style head bolts to put it back together. Ran good for two seasons but now it's pushing water out the overflow. Will do a CO2 test tomorrow. Did not like the head bolts and OEM style of torque by degrees so I'll be going with ARP bolts or studs and old style torque. Which is the best way to go?
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From: Central Cal.
I would just do the ARP bolts and go from there.
I don't know if you have new head gaskets yet, but this would be a prime opportunity to gain a little compression via thinner (.040" or so) head gaskets. It would tighten up your quench also, which would add resistance to knock. Just an idea....
I don't know if you have new head gaskets yet, but this would be a prime opportunity to gain a little compression via thinner (.040" or so) head gaskets. It would tighten up your quench also, which would add resistance to knock. Just an idea....
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From: Seattle
Arguments for the OEM bolts are lower cost, and generally they're going to work for most of the applications out there. The ARP studs are nice if you are anticipating taking the heads on and off a few times, obviously the GM bolts are a one time use deal. The other part that really makes sense to me, and I'm no engineer, is that with the studs you're clamping the cylinder head to the block with the stud stationary in the block. Just my .02
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From: PDX-OR-USA
A bottoming thread chaser tap is priceless for prepping a head, it allows cleaning the threads all the way to the bottom of the hole and doesn't take metal with it.
You get them from pro machinetool suppliers and yes it will sting when you buy it. ($$)
You get them from pro machinetool suppliers and yes it will sting when you buy it. ($$)
Last edited by pdxmotorhead; Feb 5, 2022 at 09:04 PM.
Thread Starter
Joined: Mar 2014
Posts: 699
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From: Alamogordo, NM
Well curve ball. Tested the coolant for CO2 and it came up negative! Indications are no exhaust getting into the coolant. When I run the engine coolant is pushed out the overflow but the thermostat seems to be working correctly (checked with heat gun). Shouldn't have much coolant left in the system but head temps appear normal when running. I guess next step is to do a compression test. Any ideas?
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Ususally blown headgaskets lead to white smoke coming from the exhaust or coolant mixing with the oil in the pan. Sure you don't have a clogged radiator, faulty pump or trapped air in the system? I would imagine that you would have overheating issues if this was the case though.
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Verdad Gallardo I had a problem with keeping coolant in the LSX engine after replacing the radiator. When the engine started heating up and building pressure in the system it would eventually start pushing the coolant out of the radiator. There was a lot of trapped air caused by myself for not getting the front end of the vehicle elevated up higher and slowly adding coolant until full. Once I did that no more overheating and seeing my coolant come gushing out all over the driveway.
Thread Starter
Joined: Mar 2014
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From: Alamogordo, NM
Everything has worked just fine for the last two years and suddenly this crops up. Got to thinking "what has changed, what have I changed?" The heater mixer valve leaked and I took it out of the system and just piped it into and out of the heater. Right from the water pump to the heater and back. Would this cause a problem?
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story time with bob cratchet
long time ago i was driving up a mountain in the middle of winter to a sledding hill. car was a 2001 buick lesabre.
by the time i got to the top of the hill, the car was puking coolant everywhere. wasn't overheating and wasn't burning coolant. just puking it. on the plus side it smelled like waffles. on the not plus side i couldn't fathom why the car would be having cooling issues in the middle of winter with snow on the ground.
root cause? bad radiator cap. the coolant system needs to be pressurized. without pressurization, the boiling point of the water/coolant mixture is too low for normal operation, and the coolant will boil. which, of course, causes coolant to puke out the overflow.
long time ago i was driving up a mountain in the middle of winter to a sledding hill. car was a 2001 buick lesabre.
by the time i got to the top of the hill, the car was puking coolant everywhere. wasn't overheating and wasn't burning coolant. just puking it. on the plus side it smelled like waffles. on the not plus side i couldn't fathom why the car would be having cooling issues in the middle of winter with snow on the ground.
root cause? bad radiator cap. the coolant system needs to be pressurized. without pressurization, the boiling point of the water/coolant mixture is too low for normal operation, and the coolant will boil. which, of course, causes coolant to puke out the overflow.
Thread Starter
Joined: Mar 2014
Posts: 699
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From: Alamogordo, NM
Good story BobC. As of yesterday I have been thinking about the cap and could it cause this problem. Glad you shared the story. My cap is one of those geewiz chrome ones with a junk cap under the chrome. Today I'll go get a "normal" cap and give it a try. Shore would be nice to have an $8 solution vs new head gaskets.
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If you drained coolant out of the engine you may have a steam pocket in the head. I've had good luck starting the engine, getting it up to temp so you can see coolant moving thru the radiator tubes and loosening up the temp sensor on the left hand head letting it burp out any air trapped. Don't over tighten the sensor it will break off ask me how I know.
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From: PDX-OR-USA
Vacuum filler for the win. 
I had to buy one for another project and it came in early so used it on my jeep/ls.
Mix the coolant in a 5 gal bucket, attache the tool to the radiator, drop the pickup tube in teh bucket of coolant,
turn on air to run the vacuum generator,, 3 or 4 minutes, flip 2 levers and the coolant fills up in about 30 seconds. NO AIR>> Whooo Hoo.
If only I had one back when I owned a British car.. LOL
I had to buy one for another project and it came in early so used it on my jeep/ls.Mix the coolant in a 5 gal bucket, attache the tool to the radiator, drop the pickup tube in teh bucket of coolant,
turn on air to run the vacuum generator,, 3 or 4 minutes, flip 2 levers and the coolant fills up in about 30 seconds. NO AIR>> Whooo Hoo.
If only I had one back when I owned a British car.. LOL
Thread Starter
Joined: Mar 2014
Posts: 699
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From: Alamogordo, NM
Put the new cap on yesterday and went to a small car show. Got home and was afraid to look under the car but this morning finally got up the nerve and looked...no puddle. Appears that my "blown head gasket" was just a faulty radiator cap. Feels real good to have an $8 fix.
Learned several things. One is to define the problem. This may require several test as well as research. Try to prove the initial thought is right or wrong. A part may appear to be OK but may need a test to prove it works as designed. Above all, keep an open mind.
Thanks to everyone for their input. Valued.
Learned several things. One is to define the problem. This may require several test as well as research. Try to prove the initial thought is right or wrong. A part may appear to be OK but may need a test to prove it works as designed. Above all, keep an open mind.
Thanks to everyone for their input. Valued.
Man, this might sound stupid, but it's nice to see someone ask for help, LISTEN to other members, and actually take the free advice given, and fix a problem, without saying what they know it isn't. Glad to hear it was a $8 fix! Good deal!
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