mc360

So I bought a 92 ext cab 3vze pickup back in march, it smogged just fine but after I smogged it I got a cel for lean condition. Not sure if this leads up to the head gasket (I'm sure it could if it was really lean) but I got new plugs, new o2 sensor and a new water temp sensor on the back of the motor but I still have that damn cel light.

Anyways I have read that deleting the crossover and installing an MLS gasket should cure the problem and I was thinking of getting head studs also. Now the problem is I contacted Ted at engnbldr and asked his advise, he said that an MLS could help but will also fail at some point from the head and block being different materials and moving at different rates, he also says that extra clamping force from studs won't help so now I'm not sure what to do. I really don't want to pull the block out to surface it for MLS gasket but if it needs to be done to make it last then it will get done. Truck has 245,000 miles and has already had the head gasket done by a dealership at one point

Smaay

he might know some things, but his info on dis similar metals is pure BS! we use MLS gaskets in 2JZ and 3S-GTE engines all day long. iron block and aluminum heads. and he is wrong about the clamping force using studs too.

however in stock power applications, head studs are not needed.

mc360

Thanks for the reply, I know studs are not needed for stock but they seem to make installing the gasket and head much easier and also with stronger studs it seems I could torque them down much more rather than the 35ft lbs +90 degrees +90 degrees. That torque method just seems assanine to me, I'm sure just studs get torqued down to 70ft lbs or something.

Smaay

35lbs plus 180 degrees is pretty good torque. im not saying you cant use studs, just saying they are not necessary.

mc360

It might work out to a good number but the 90+90 seems like it can have a lot of variance in it, I have read up to 12ft lbs variance which is a lot. I don't understand why toyota doesn't call for 2 steps, one at 35ft lbs and one at say 70ft lbs or what ever the 35+180 degrees comes out to.

mc360

Has anyone here tried installing a MLS gasket without surfacing the block? I emailed Lcengineering and they said if you can't feel any scratches with your finger nail it should be a smooth enough finish to seal, I have not pulled my heads yet but I want to start ordering stuff.

My plan is to replace:
-Head gaskets
-Head bolts with arp studs
-Timing belt and water pump kit
-Injectors (mine are disgusting so I will pick up some flame throwers)
- knock sensor (not sure if it's possible to leak oil but it has oil all over it but I didn't have a check engine light on for it so it must be working?)
-knock wiring harness

Truck had a check engine code for lean condition and after seeing those injectors I believe that I possibly have a clogged or bad injector. Pretty much doing a full overhaul minus a bore/hone and piston rings, I'm looking at about $1000 right now and I might have a shop check valve clearances while the heads are off. Oh and rebuild that stupid exhaust crossover

RJR

I wouldn't assume I could design a better head torqueing strategy than Toyota. They have multiple units they can test and run until failure, throw them away, and start over. You don't have that much money.

The 35 ft-lbs+90+90 is designed to get more uniform clamping pressure, not less. Keep in mind that accurate clamping force is what you're after, and torque is only a very indirect indicator of clamping force. Depending on thread lubrication and smoothness, any given applied torque can easily translate to a 2:1 variation in clamping force. The angle torque method greatly reduces those variations - it makes clamping force a function of thread pitch and bolt modulus of elasticity, variables which are much better controlled.

Also, with respect to your thoughts about installing studs so you can increase the torque and clamping force; that's definitely not a good idea. You will increase pressure next to the studs, but in the process will likely over crush the gasket and warp the head, leading to reduced clamping forces between the studs and a gasket failure at that point.

BTW, you haven't said why you think the head gasket is bad. All I saw in your post as to symptoms was a CEL for a lean condition. That could be, and likely is, something entirely different from a head gasket.

mc360

Sorry I thought I put that in there, oil is all frothy and coolant was low. Man this is getting harder and harder to decide on studs and MLS or stock, I think toyotas are great but I don't think toyota designed the 3vze good enough or they wouldn't have this problem. Also this truck has had the service done on it before and the issue was not cured so once again it was not done correct

superex87

The main reason a head gasket fails is due to over heating. If the cooling system on the 3vze is not 100% you will blow a head gasket. All so Toyota's like to have very small leaks at the head gasket, the engine will continue to run just fine with a small loss of coolant over time. This condition will suddenly get worse, that's when you realize the head gasket has failed. So its more than possible that the previous repair guy slapped on new gaskets with out resurfacing the head. This would fix the big leak but not the little one. Old engines all so tend to suffer from corrosion around the coolant ports on the heads. This is due to lack of coolant changes (if any). Put new Toyota or Fel Pro gaskets on it and follow the factory service manual. Get both heads resurfaced and it will not be a problem any longer.

Due to the crossover design the valve clearances need to be checked every 60k or so. Not doing so WILL lead to burnt exhaust valves (this can be applied to any engine with non-self adjusting valves)

A lot of people like to blame bad design but if the maintenance schedule was followed it would be rare to have a failure.

mc360

As far as I can see I believe this "overheating" is caused from the crossover because my truck has not overheated once since I have owned it in the last year. I was planning on running a straight edge on the head to see if it's within spec if not I will get a resurface done on both heads. Also if my truck really is lean like the check engine says then that could be a contributing factor to blowing the gasket and that would be an error on my part, I bought the truck and smogged it then the check engine came on. I replaced the o2 sensor, replaced the coolant sender (I believe that's the one for the ecu) and spark plugs but still have a check engine.

My next step was going to be replacing the injectors (mainly because I have read a lot of good about flame throwers) but also because the Haynes manual says bad injectors could be the issue. I haven't had money to spend or the will to tear the intake off just to try it but now that I have seen the injectors I ordered the flamethrower finally, next thing I need to order is cap and rotor.

skypilot

iTrader: (1)

Here is my deal. Go get the ARP head studs. Have the cylinder heads done right and put a new set of camshafts in(wear item). Use a factory HG and torque to ARP specs. Problem solved.

You don't need to stud the heads, but it does make the clamping force more even, which is what you are after. Nothing wrong with TTY bolts, just get the right tool to set them with, before you start.