There is so much talk on the forum about the 3.0 and the notorious head gasket problems. But there is little talk of the actual cause for the breakdown itself. I have herd that overheating is a symptom of the blows but that is about it. Does anyone know what is the root behind the 3vze head gasket problem and why it happens?

 

What I know, is that the stock manifold on the 3vze is very poorly designed. It wraps around and circles back upon itself, becoming hottest at the #6 cylinder, superheating the valves and head area, causing the gasket to fail.

Headers are a great solution to this problem as the exhaust does not need to be restricted by the stock manifold. I have been told that headers are very important in the 3vze because of this.

I've also heard that cams help with the heat issues but I don't know why, exactly.

My knowledge on this is limited, but I am following this thread and I know that you will get lots of great answers from the devoted 2nd gen crew on this section of YT!

 

like taikowaza said, the poorly designed exhuast crossover doesnt' help the cause. Headers are an awsome idea. Also make sure your cooling system is up to par and working properly.

 

well, I say that's true for ANY motor, or vehicle for that matter lol


do the 3.0's have aluminum heads with a cast block too? I know that usually can cause issues too, like on the 22re's

 

It's a combination of bad block/head design and bad exhaust design. There is too little distance between a couple of the water galleries and the #6 and #1 cyls (they're almost a mirror image of each other). The width is not much more than the steel sealing ring - just a few millimeters. That's a problem because the block is iron and head aluminum, as mentioned, and the two metals have different expansion rates as they heat up, causing them to move past each other. The gasket is too narrow in those areas, and can't hold up to much movement. The bad exhaust design causes #6 especially to get too hot, causing more heat/expansion/movement which is why the gasket fails most often around that cyl.

#6 left end of top photo; #1 right end of bottom photo:



Some of these gaskets have been redesigned to increase the amount of material in the weak areas, but that material just hangs in the midst of the passing coolant stream - it isn't pinched between head and block and doesn't do all that much for strength. Some, but not much. And it obviously partly obstructs coolant flow, which decreases cooling, obviously canceling some of the advantage. Rock Products is one of the ones with the slightly improved gasket design:



IIRC, the redesigned gaskets I got from the dealer were an even better design, with a steel and graphite sandwich, but it's been 8 years since I replaced them, and I forget exactly what they looked like.

The best gaskets for this badly designed engine are mls - multi-layer steel. If installed correctly, they are almost bombproof, but they require milling both block & heads to a mirror-like flatness and smoothness.

Headers are a great mod for this motor, and be sure your EGR is working well since its purpose is to keep combustion temps down (to reduce formation of nox, but it helps protect the head gaskets, too).

EDIT: I've read that the Rock gaskets also incorporate a steel slipperplate 2-layer design, in which case they may be a good cheaper substitute for the dealer gaskets. There's a Rock Products complete cylinder head gasket set available from rockauto.com for $137 - looks like a nice quality head set for a nice price.

 

what iv learned from my 3.0 is:

crossover pipe- very poor design, very little air flow to back of engine. that thing gets hot . its a horrible design especially because the exaust flows in reverse for a bit before it flows throught the down pipe.

head and block- aluminum head, iron block, all that needs to be said

poor cooling system design

the one major thing i can suggest is keep up on your cooling system if u cant afford the $500 headers. an overheating is a death sentence for a 3.0.

theres some stuff called "wetter" that u can get at autozone or advance. u have to flush the cooling system then mix it in with new coolent but its worth it. i dont know a temp but you can see the change in the temp gauge for sure.

anyway theres my two cents

 

Weasy2k told me when I got his improved cams that this also helps with temps. Can anyone explain why performance cams can help w/temps? ps love his cams sound great nice performance too. Don't think he's selling them anymore but he might if you contact him.
Weasy2k's 3vze cams were created by coltcams and Weasy2k is the sole distributor.
This might be worth a read re: these 3vze cams and temps.


Click for full size - Uploaded with plasq's Skitch[/IMG]

 

my guess is that all of the posts here have some truth to them and i certainly wouldn't be the one to say they don't, however; if i recall correctly that problem was a factory recall and fixable at the local dealership as the problem "usually" reared it's ugly head before or around the 100k mark. i've owned six (and still have three of those) and have never had another issue with that area--they were all done in the recall phase and are running in the 200k plus range now--they have ranged from '90 to '94--interesting, no?

 

All good points so far. Let me add the use of cheap aftermarket head gaskets. When my hg blew I took my head to be done and the machine shop offered me a "deal" on a full gasket set, since they needed the head set. Not being familiar with the 3vze issues and generally working on iron blocks and heads I fell for that. Gasket layers didn't even look that well laminated... but I used it anyways. Only about 10,000 miles on it until it totally came apart. There are a lot of lame manufacturers out there and plenty of these junk gaskets get installed.

 

Hi this is my first post. The story we got at the dealership when this problem originally started was the outfit that was manufacturing the headgaskets had a design flaw. At the beginning of the recall we as technicians noted the replacement gaskets looked identical to the originals, we were authorized to replace long blocks and or cylinder heads if nesseecary. Lot of folks got new blocks due to bent rods and such , also if the clyinder head could not be remachined within specs, they got a new head. I saw alot of warrenty repairs reoccur over the years but as time went on the headgasket recall seemed to stabilize, wether they got the headgasket corrected??? who knows. If mine was to fail in this manner today I would definitley be using OEM gaskets, over time they seemed to get it right. IMHO
Pigman

 

i heard that they put some in upside down in the earlier years but after early 1995 they fixed it because thats when they came out with the new tacoma with the 3.4

 

Never found any upside down, really don,t know if thats possible. By late 95 , Toyota seemed to have the problem taken care of , I believe the vin cut off for the campaign was in mid 95. My wifes 95 4Runner does not fall within the vin# range and has 260k on it with no problems. After we got into the 3.4 liter engines the problem was a few had external headgasket leaks and Toyota was all over that!
Pigman

 

Thanks for all the good posts. Still haven't made up my mind if I will get another toyota with the 3.0 or the 22re but i know now that you must keep the 3vze nice and cool to make it happy.

 

Some performance cams will increase the overlap between intake and exhaust valves. This means that as the exhaust is being forced out by the piston, the intake valve is opening and some cool air from the intake is going to be sucked in and cross-flow through and out the exhaust.
Who knows, really though?