williemon

Got a big problem. Back in the early summer I got my 4 runner back from the shop that had repaired the valves for me. The heads were reworked and ported and polished from DOA and the cams reground. The origional problem was that the #3 cylinder had a bad valve. During this work, the shop had a hard time getting the air out of the system. It would idle ok, but when they started to drive it, it would start to get hot. The finally took it to a place that had a vacume machine to pull a vacume on the system and suck the antifreeze water into it. When they got it back, all seemed well. It took about 4 miles of running to get to temp in the mornings (70 to 80*) but got to proper temp and stayed. It ran fine and all seemed well, untill the seasons changed. Once the air temp got to 65, it would take longer to warm up. At 50*, the engine would not warm up and would not go into overdrive. I thought that the thermostat had stuck open. Bought a toyota thermostat, went to put it in and found that the one that was in it had been modified. the spring and plunger had been cut off of it leaving an open hole at all times. No wonder it would not warm up now. I replaced it, but I could not get it to stop running hot now. I tried my best to purge the air out. Finally I put the old one back in and went back to the shop. They were sorry that the thermostat had been modded and assured me they would make it right. So they worked on it all day and finally got it fixed. So we thought. I drove if that day and all seemed fine. It got to temp quick just as it should have. I ran for about 5 to 8 miles like that, then the guage started going up. I just let it run and it would get close to the red, but would never go on up. then it would fluctuate between slightly overwarm to quite a bit warm, but never in the red. It did this for a day and would leak coolant from the top hose, but not boil over. I finally took it to the dealer and they ran the infrared sensor on it and said even though the guage showed it was too warm, it was still in spec. They also did the block test to see if exhaust gasses were in the coolant. No problem there. Ran a compression check, no problem. They found the upper hose clamp was not tight enough and replaced it. They felt the coolant temp sensor may be sending bad signals to the guage and wanted to replace it. I was skeptical at this point, but was out of time so I went on back to work. That evening going home, i was running the heater. I got hot and turned the temp lever to cold. The engine temp guage then climbed into the red. I turned the heat back on. It was very hot. It stayed just at the start of red maybe 1 mile. Got home and pulled the hood and the coolant was boiling in the upper hose, but not spitting into the overflow tank. I let it cool a little, pulled the cap and let it sit. I then topped it off and let it sit overnight. This morning the level was down a little, so I pulled the upper hose and added coolant into it untill it was pouring out the radiator. Put the hose on, and topped off the radiator. drove to the dealer, with the engine running halfway between the middle and the red zone. I used the heater and kept rpms below 2500. I told the dealer what happened and he said sounds like a head gaskit and that they would at this point want to pull the heads. The other shop i took it to says it still sounds like air in the system. Ok, now my thoughts:

1: If the heads or gaskit or block were at fault, would the engine overheat even if a modified thermostat were used?

2: wouldn't there be some other indication? loss of coolant (other than being spit out) residue on the oil filler cap? Loss of power?


As a side note, one of the service writeup guys I was talking with said theres one bolt on the top of the engine that you take out, and any air in the cooling system would come out of it and when you get a steady stream of water, you reinsert the bolt and all is done. Anybody know anything about this?
Im going to paste this on a few other boards to see what might come up.

dusty98

This coming from my memory so here goes:
I read somewhere, don't remember where, that you can install one of the headgaskets backward and it'll block one of the cooling ports in the head. You won't know it till you put everything back together and it overheats.
I would think all that should be covered under warranty from the shop who did the original work. Whatever it is needs to be handled before you blow up your engine.
Good luck,

williemon

More bad news. The shop that has been doing the work on the runner from the beginning has tried for 2 days to get the system to not overheat. Not happening. They have called on many of their peers for advice and it all points to the same things. Must be a problem with the heads, gaskits or block. Either way, a teardown is going to have to be done and they want to pressure check the heads. I asked if they may have swapped the gaskits or put them on upside down by accedent. They said that the gaskits only fit one way so it couldent be that. They used the Toyota gaskit kits, so does anybody know if they could be put on wrong by accedent? They are going to do their own compression check tomorrow before the teardown. As it is, a Toyota dealership did a compression check, and a chemical block check to see if exhaust gasses were in the coolant. All was fine. The entire cooling system is brand new except for the fan clutch. There has never been any loss of coolant(except that which has spewed out due to getting to hot as of lately) and no contamination of the oil. No pinging or loss of power. With the modified thermostat acting like a stuck open thermostat, in 70 to 95 degree weather, the engine will reach operating temp and hold steady. With the non modified thermostat in place, it overheats. Any ideas? Could the block be etched ever so slightly at the head gasket mating surface causing an overheat, but no other symptoms? The shop has been very fair to me and has done their best so far to make it right. Anybody have any ideas or thoughts on what parts I should again pay for during this teardown? Any ideas as to what to look for and how to trobleshoot this? Like I said, the mechanics are doing their best for me, but they are stumped. Anybody know if the head gasket recall might apply if the block mating surface was etched even though ive been told the vin is not in the range? This is a 90 4 runner by the way. Thanks all.

Jay

Sure sounds like a tough one.

*Yes you can have the head gaskets on backwards. However you would end up bending the rear of the drivers side gasket to fit around the valley coolant tube. Its been done, Ive seen it. Similar symptoms.

*Is the radiator restricted?

*There is no bleed screw on a 3vz-e engine. Typically people have been just removing one of the throttle body cooler hoses from the intake to bleed the air out. I however just remove the upper hose from the radiator and bend it upward and fill. I have had no problems.

My $0.02.

Jay

williemon

I got word from the shop that had been working on my 4 runner that they had indeed installed the head gaskets on backwards. They also pressure tested the heads and they were ok. There in the process of getting the gaskets and new head bolts and getting my injectors cleaned. Thanks all for the help!!

williemon

Im going to get the injectors flow tested and cleaned today. 85 bucks if I bring them to the place here in town that can do it. Wish me luck.