Part 2 Reassembly on a head gasket change for a GM 3400. Basically the same as a 3.1 Engine. Here are a few torque ratings that I used while I was putting it…
Part 2 GM 3400 How to Replace a Bad Blown Head Gasket Reassembly Overheats No Vent Heat 3.4 Liter
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12-14 hours. Best way to do it is take it all apart one day and clean it all up. Next day put it all back together.
VT247
The compressor bolts need removed but you don’t have to evacuate the a/c lines. Leave it hooked up and just set it aside. The other bolts for that bracket are behind the a/c pump. It’s sometimes difficult to remove that bracket, it has a hole up top that you have to twist and turn the bracket and pull up to get it off.
VT247
How many hrs. is this 3.4 job?
I noticed the bracket passenger side front needed the A/C compressor taken loose, what bolt is holding it in place down low, I hope the Compressor doesn’t need to be taken out
completely just bolts out and laying on the sub frame????? What a pain no book for my 2002 Buick Rendezvous 3.4 L. Using a chilton for Aztec etc. Decided to replace head gaskets as well and timing chain, Engine milked, lower intake failed. Let me Know. Steve
I didn’t have to machine my heads any of the times I did this job. I’d only machine the head it it has pitting and really needs it. Use heavy duty head gaskets by Fel Pro this time. Should keep from having to do this job again if using HD Fel Pro.
VT247
I had to have this done on my 2000 Silhouette 5 years ago, and now it looks another blown head gasket. I’m going to attempt doing it myself this time. When my mechanic did it the first time, he had the heads machined. Is that something I should do as well? Thanks.
The rocker arms studs have grooves in the bottom of them. They set into the head into the slots. They are bolt down and go, I torqued them to 50 ft lbs. The pushrods are different lengths for the exhaust and intake. Make sure they are in the right location. Good luck with your fix.
VT247
I have a 2003 Chevy Venture and I am certain the head gasket is blown. Your video was really helpful for when I stat but I have one question as of now. I noticed that you didn’t adjust the rocker arms like is needed for the older model engines, like a 305 or 350…is this because they do not need it as they just bolt down and its good to go? Thanks so much.
It’s the head gasket, sorry for the bad news. It’s not that bad of a job to do, just time consuming.
VT247
I have a alero 3400
My car over heats, don’t blow out heat when I the heat on in my car, it’s leaking and when I put coolant and inter-freeze in my car it grains right out sometimes. Last a couple of times when I put it in my tail pipe blows out white smoke.
How do I know my head gasket is blown?
Oh yea! Dual overhead cam engines are not easy to do a head gasket job on.
VT247
I pulled out my shop manual and my chiltons to see what the procedure was for changing the head gaskets on my engine – yikes! Not something i’d ever feel comfortable doing – looks like the cost of a replacement crate engine would be less than having it done – plus there’s no guarantee the heads would be good to reuse (i had an overheating issue when the auto belt tension thingie failed.)
No, it’s not the same. I believe the Monte Carlo Z34 has a dual overhead cam V6.
VT247
Is the 3400 you worked on the same 3.4 liter engine that’s in a 1997 Monte Carlo Z34?
Hopefully the mechanic didn’t strip out the threads for the rocker arm or put in the wrong length pushrod. The threads for the rocker arm studs can get stripped out that go into the head. Also, the pushrods are different lengths for the intake and exhaust. Of course, in order to find this all out, the valve cover has to be removed. Feel for slack in the rocker arm while not in lift.
VT247
I’ve just had the manifold gasket replaced by a local car repair shop on my 2003 Pontiac Montana 3.4 liter engine. Seems OK, with the exception of a tappet noise on the back 3 cylinders. I cannot tell which specific cylinder. I’ve spoken to the mechanic, and he believes that one of the lifters did not push up. Rather than having him rip into the engine again, I’ve just changed the oil using Mobil-1 Synthetic, replacing one quart with Hi-Tach oil additive. Can you provide any advise?
All kinds of bad things happen when a car overheats. But it also depends on how long it ran in the red for. Obviously something is wrong though, spewing lots of smoke out the exhaust and overheating. The heads could be warped, the catalytic converter can get plugged up from the junk going through it, the block can crack, etc. Sounds kinda shady on both the supplier and the warrantor part IMO. The supplier for the engine breaking in 6 mo and the warrantor for the intake issue. SMH
VT247
The engine was from a remanufacture (supplier) to an instalation garage (warrantor) , at least that is what he says. I filed a breach of warranty complaint in The court because he charged me to change the intake gasket after the first time the remanufactured engine overheated. He wants to honor the warranty now. I anticipate he will do a pressure test on the head gasket since it overheated again into the red zone. If it shows to hold, do you think it has been damaged by the overheat?
Not sure what kind of engine you purchased (junkyard?) but it sure sounds like a head gasket failure. If you bleed the air out from above the water pump and the thermostat housing then drive it and it overheats quickly then have to bleed more air out of the system. The head gaskets have failed. Watch part 1 of these videos and read the comments. It will help you understand what’s happened. Best of luck, hope you get it fixed without a lot of expense incurred.
VT247
My 2000 Pontiac Grand Am engine was replaced by a professional with a warranty on the engine. It ran for about 6 months then overheated again. They replaced an intake gasket and said the intake was pitted, but put it back together without milling. They said the radiator fans are not coming on properly and gave it back to me with the fans unplugged to keep it on continuously.It oveheated again and blows thick smoke out the exhaust. Does the red overheat light mean head gasket failure imminent?
If you’ve replaced the head gaskets, thermostat, and water pump, then bleed the air with the bleeder on top of the thermostat housing and water pump. Also check for water flow with the engine running and that the system builds pressure.
VT247
I remplce the head gasket on my chevy venture 2001 has new whater ponp thermosta still overheat I don’nt what os todo any help please.
I’ll try and describe what’s happening inside the engine. With a blown head gasket (BHG for short) the coolant can’t pressurize correctly no matter how many times you bleed the system. Piston goes down, the coolant is drawn in the cylinder at times. When the piston goes up, the air and exhaust gases enters into the coolant passage. You’ll typically see where the head gasket has failed once the heads are off. The cylinder with the BHG has a clean area from being steam cleaned from coolant.
It’s the head gasket. How do I know? My Aztek (same GM 3400 engine) did the same thing before I did this job. Don’t bother with any head gasket fix in a can. It won’t fix it.
Probably not the news you where wanting to hear, but until you fix the head gasket, the problem won’t go away.
Watch at the 19:10 mark. You’ll see the head gasket and how it’s failed.
VT247
If you could email me at willievalead24@gmail.com id appreciate it
How did u know it was the head gasket that was blown?? Im going to do the same job but not sure if im doing it for no reason I have olds alero with the 3400 it overheats no matter what I do.. ne water pump. Thermostat I bled the system and it will b fine for about 5 miles then overheats and water comes out the overflow is there only the one bleeder?? I couldnt find but 1 anyway please help
With the upper intake I torqued each down even by hand going in a criss cross pattern. Hand tightened each one in steps. There is a metal insert on the Fel-Pro gasket that causes the middle runner to break, #3 cylinder. Tried not to be to aggressive with the torque as I made this same mistake. Couldn’t figure out why I had a random misfire on cylinder #3. To much air entering the combustion chamber causing a miss.
VT247
I was just wondering how much you torqued the upper intake manifold down. I cracked the original intake manifold, then another used intake manifold – I think the torque was at about 2-3 ft-lbs when the second popped. The repair manual spec was 18 ft-lbs, but that seems to be very wrong.
The engines are interchangeable. Some of the vacuum tubing and such might need swapped if swapping from a car to a van or SUV. Most junkyards and websites should be able to give you interchange info. Think most all 3400 are the same. Heard some had smaller intake ports but all the one’s I’ve seen are identical.
VT247
Is there a difference between the 2003 and 2004 versions of the 3400 sfi?? I am trying to buy a new engine and most are for 2004 models. Are they interchangeable?
That is a good idea. Will do this next time.
VT247
I’d check vacuum first. Make sure the map sensor and all connectors are fastened. EGR, fuel pressure regulator, rear vacuum hoses, firing order, coil pack & module. Throwing out some areas to check.
VT247
It’s best to put you rear bank plugs in prior to puttingyou head on the motor. I also hooked the wires to the plugs numbered them and zip tied them out of the way for the rest of the motor assembly. It will save you time and a head anch at the end of assembly.
Sorry to bother you so much. We got this finished tonight. started the car and at first it ran better than it has since we bought it. after running for about a minute to minute and a half, the car started chugging and trying to die. the tach at first was holding about 700ish. when it started chugging, it would dip down to like 300 and 400, then back to 700, and then right back down. after about 30 seconds of this, the car would die. brother thinks vacuum leak. any ideas?
You don’t have to clear the rest out of the block as long as it’s the green antifreeze. I’d add 50/50 mix. You don’t want the weather to get sub freezing, the water to freeze up and break something from expansion.
VT247
Just finishing this job up today. Brother helped. Dont know if its a major issue or not, but he did not drain the coolant from the block, jus what we lost from hoses and thermo. Should we drain the rest and do all new or are we good to just top off? Also, he wants to just put water in with whats still in there. I say the 50/50, but hes insisting water and whats still there will be fine. Which would you do?
Yes, I left the valve springs on. They reset back into the head once the rocker arms are loosened and off. I also left the crossover exhaust tube on and had a friend help me lift both off at the same time : D
VT247
Excellent Job, but did u take the heads off with the valve springs attached?
Even if another engine is put in, the 3400 engines typically all have this problem. I’ve done the head gaskets on both my 2001 Pontiac Azteks and just this month drove 2500 miles from Indiana to California. Both pulling a trailer, through the desert, up and down the mountains without issue. Used Fel Pro Heavy Duty head gaskets not had any problems.
VT247
called back the mechanic to get an estimate on having him do the heads… unfortunately he said he wouldn’t do them and instead recommends putting a new motor in it. says if heads are done, im gonna have the same problem 6 months to a year down the road. looks like ill be rewatching your video 5 or 6 more times and doin this job myself.
Bummer. To bad the intake was just done, it’s best to do the head gaskets at the same time. I’m pretty sure the head gaskets are bad. If the 7mm air bleeder has been bled and it still overheats. It’s the head gaskets. The thermostat rarely sticks closed.
VT247
Have a 2002 aztek with this motor. started overheating and no heat in feb, got into garage an mech replaced intake manifold. got back and still overheating and now is starting rough and idles rough when cold. is my head blown? no white smoke and every time ive checked oil, it looks okay to me, but not the most mechanically inclined.
And install the head gaskets dry, no sealer on them.
The bolts are torque to yield for a reason, follow the factory torque sequence. For the 90 degree step, draw a vertical line on the top of the stud and then turn this 90 degrees from that point.
I usually dont comment like this, but just about every tip you mentioned made me cringe. Head bolts go in dry or with a very light coating of oil on them. All head bolt holes get blown out with compressed air to get any liquid out that could crack the block. Place the dowel pins on the block, then the head gasket on the cleaned block surface. Lay the heads down then.
by the way i thought it was just leaking at the thermostat houseing and had been able to just add coolant every other day,after running hot this last time it was running pretty rough got it home and my radiator wasnt filling up,i guess the gasket went all the way out on me,stop leak probly wont help me at all now would it