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Blown Head Gasket???

03-23-2009, 02:42 PM
I have a '99 Blazer, 4.3L, 4wd, 154k miles driven mostly in South, and have overheated 1x approx 3-4yrs ago due to clogged radiator, which was replaced. I recently (2 mo ago) had intake gasket, thermo, water pump, and cap replaced due to coolant leak and belt "squeal". That was the 2nd intake gasket replaced since 2002.

I am now losing small amount of coolant and getting the white exhaust smoke at startup then disappearing after 5 or so minutes. It idles a little rough sometimes at startup for 20-30 sec and then is fine. I just replaced the spark plugs yesterday to see if they would show me anything, the only bad one was #6 and it did show signs of wear but it was 100k since replacement. No signs of coolant in oil or oil in coolant like the first time I replaced the intake gasket. I hope it is not the head gasket but am leaning in that direction. I would appreciate any diagnostic assistance you guys may have on this...

03-23-2009, 03:05 PM
Only way to tell for sure is to do a compression test on all the cylinders.

03-23-2009, 03:47 PM
I would do a pressure test on the radiator run the engine with the tester on the radiator. Normally a pulsing gage will be a sure indication of a blown head gasket.
A radiator shop can do a gas analysis on the radiator fluid combustion gas in the sample is a sure indication.

03-24-2009, 06:58 PM
Exactly what mine was doing, no mixture of oil and antifreeze. Rough starts that leveled out after 15-20 seconds. Got worse as I let it go. Also, resoirvoir was full, but radiator low. The compression build up from the exhaust leaking into the coolant wouldn't let the coolant suck into the system from the resorvoir. Shop did a check on the antifreeze for $20 bucks and found signs of exhaust in the antifreeze.

Mine is 2.2, 230k, didn't want to put much money into it, so I bought some Bar's leak Head gasket fix for $24 bucks. It's been four weeks, and so far so good. Probably wouldn't trust it in anything worth fixing, but it is doing the job for me.

04-06-2009, 03:54 PM
Took it to the local dealer today and sure enough it is a blown head gasket, #6 cylinder taking in fluid. $1500.00 later and I could have a 10 yo Blazer w/ 155K miles that could take another ^ any day. $2000.00 in repairs within the last year, I think its time to invest in a newer vehicle a little closer to the top of consumer reports' reliability scale! Maybe I'll try to fix the Blazer myself and keep it for a winter beater...its been a long strange trip.

04-06-2009, 04:25 PM
If you can't repair these trucks yourself they are definitely a MAJOR burden on the wallet. I just replaced the intake gaskets myself, cost me $150 VS $1200 it would have cost to get them done. I just replaced my heatercore which cost me $130 VS $1300 to get it done. Nevermind all the other work I have done. I have about $1K in parts + I paid $1200 for my truck last year so I am still happy, but I can see how it would just make anyone sick to have to pay hte repair bills for one of these trucks.

04-07-2009, 09:48 AM
Ok, I am going to give it a shot. I figured, what's the worst thing that could happen...wait for it. I will follow the how-to for the Head and Intake. I am sure this will be a challenge but one that will feel really good upon completion. Bloody kuckles and greasy elbows...

04-07-2009, 07:09 PM
Head gasket failure is not real common on the 4.3L. When you remove the lower intake manifold, check the gasket very carefully between the #6 intake port and the coolant passage for any signs of poor sealing. That's a very common place for the intake gasket to leak. If coolant leaks past the gasket, and finds its way into the intake passage, white smoke out of the tail pipe could fool a rookie technician...or maybe he's trying to do some unnecessary repair work ;)

04-07-2009, 07:40 PM
I'm in agreement with OM on this one. Last Nov. I bought a 97 Bravada with a supposed blown head gasket and one head unbolted. I towed it home, ripped it down, and the gaskets were good. There was lots of evidence of the intake leaking though. Since one head was already unbolted and he gave me the gaskets with it, I went ahead and replaced the head gaskets. There was 143k miles on it and had less then 1 hairs worth of ridge on the top of the cylinders. Head gaskets were still whole and not leaking in any way. I got it together and it ran like new. It's really not that big of a job and everything is pretty accessible. If you want to do the job yourself its not bad. Just make sure to get some good gaskets, get new head bolts, and make sure everything gets back into its proper place.

04-16-2009, 08:58 AM
OK, things are going well I am ready to get the distributor out and disconnect the fuel lines and then onto the intake. The various wiring harness' are becoming cumbersome to work around but it seems there should be an easier way to get those out of the way and I am worried I won't be able to get the intake placed in evenly with all that stuff in the way. What are any recommendations you guys may have. I thought about pushing it all towards the firewall or disconnecting at the ecm to provide a little slack. whaddya think? Also any thoughts on the Head Puller Tool, good/bad, necessary?

04-16-2009, 05:50 PM
I always turn the crank with a breaker bar and line up the rotor before pulling the distributor.

Then check the marks on the damper and make sure they are lined up also.

04-18-2009, 10:37 PM
Well, I have just finished pulling the heads and am going to finish cleaning them up tomorrow. The #6 cylinder plug was really fouled (new 1 mo ago) and there was coolant in the cylinder. The intake gasket seemed to be fine though (replaced in Jan.) Only a few hiccups along the way, such as clearing the driver's side exhaust manifold and the rear ground bolts on the heads. Now I gotta put it all back together in working fashion!

04-19-2009, 05:33 AM
I would get the head pressure tested at a machine shop with coolant in the cylinder. Use a flashlight and lay flat on the block look for cracks between the cylinder. Some shops will vacuum test a head cheaper but its not as good.
They will use a straight edge and make sure it isn't warped.

04-19-2009, 03:14 PM
Honestly I would get the heads sent out for atleast a 3 angle valve job AFTER they are fully checked for cracks/warpage by a reputable machine shop.

04-19-2009, 08:32 PM
No need for a pressure check! After cleaning, I found a crack between the #6 cylinder and the #4 head bolt hole. Other head/cylinders/gaskets looked great. Now I need to find an inexpensive head replacement. Any suggestions and casting #'s, NAPA was reasonable but it would be nice to find cheaper solution?

04-20-2009, 07:22 AM
You can buy a used head at a junk yard and get a valve job on it. Stop at a machine shop they might have a redone used one for your vehicle. You may have to call a few before you find one. A junk yard may have a good core you could get redone at a machine shop.

04-20-2009, 11:10 AM
No need for a pressure check! After cleaning, I found a crack between the #6 cylinder and the #4 head bolt hole. Other head/cylinders/gaskets looked great. Now I need to find an inexpensive head replacement. Any suggestions and casting #'s, NAPA was reasonable but it would be nice to find cheaper solution?

Your best option is a machine shop. I know around here my shop has ready to go units for a fair price. The last set I bought I paid 300 all reconditioned and ready to go. I thought that was pretty good considering they usually charge 225 just to go through yours.

05-01-2009, 01:04 PM
All finished! I found a reasonable online vendor w/ great service for my cyl head and had a great shop clean and do valve job on the one good cyl. No major problems on reassembly, just took my time and reversed course. The how-to was awesome, thanks for those who contributed. I do however have a coolant leak in the radiator/lower hose area that I need to find soon. I am getting pulley squeal and small amounts of pooling. I hope I can find it...

05-01-2009, 07:09 PM
If you reused the factory hose clamps then just do yourself a favor and change them all now for good screw type clamps.

05-01-2009, 09:35 PM
Just finished pressure testing the cooling system today and found a leak in the radiator on the drivers side, a little pinhole up. Replaced it tonight and am having no problems with the coolant, however I did get some red fluid (tranny?) that surprisingly came from somewhere. I could not find any leak on lines to rad, but thought it was really strange. I will have to keep an eye on that...

05-02-2009, 06:58 PM
The radiator has an internal transmission fluid heat exchanger.

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