I think I maybe facing the inevitable question of life or death for my truck…

First the basics: we are talking about a 1990 4Runner V6, auto with 258k.

Here’s the deal. The other day, I was driving down the interstate and as I stopped at the end of the exit ramp, I heard an odd whistling-type noise and then the truck stalled. I looked at the gauges and saw the temp was pegged in the red. I quickly started it again and drove it a short distance off the road and let it cool. I had been on the interstate for at least 20 minutes and have no idea how long it had been running hot. I didn’t notice it until it stalled.

The radiator mounts had broke free and the radiator had shifted forward into the fan, which had rubbed a nice hole in it. Coolant was spewing from the hole and there was a nice round fan imprint on the radiator! There was also white smoke coming from the engine, I figured it was just because it had gotten quite hot.

Now, here is what I have tried thus far… I replaced the radiator, but the engine still would overheat rather quickly. I am now in the process of replacing the thermostat, but I cannot get a good seal around the new thermostat. Like an idiot, I didn’t really study the old one too well when I removed it. Is there a trick to getting a good seal around the thermostat covering? The gasket that goes around the thermostat doesn’t seem to be enough, should there be something else?

With the thermostat in place and leaking, I went ahead and started her up in order to gauge if my problems are more serious than these anyway. No need fussing with thermostats and such if the thing needs a head gasket… Sure enough it heated right up. I am wondering though if the thermostat needs full pressure to function properly (meaning no leaks) or can I assume from here that my problems are greater? Also, I have looked in the oil for signs of frothiness and find none.

I have a feeling that my truck is doomed. I called Toyota to check if my truck has taken advantage of the head gasket service campaign and I was politely told that it had not but also since my truck was manufactured in 89, I do not qualify for the ever-lasting free head gasket campaign. Drat! So much for that!

So now I am left thinking that my truck has serious problems. What would a truck with a blown head gasket run like? Thoughts? Do I put it out of its misery and buy a Ford?!

 

ouch. sounds like you're in a pickle. sorry i can't answer any of your questions. but come on buy a ford????? i hope that was a joke. no ford would run 285K+

 

Whatever you do......don't buy the FORD!

I've run Toyotas' for some 30+ years....first one I had we finally put to pasture at 480,000 miles! They run hard and long & the FORD won't do that!

Best of luck to you!

 

If the head gasket is blown, you will have water coming out the tailpipe, lots of steam, water in the oil, you will KNOW.

Why would you include a troll like that on a Toyota board when you want help?

You are dignosing the the truck with your psychic abilities and coming to conclusions like "I have a feeling that my truck is doomed", without giving us anywhere near enough information for us to assist you beyond it has given you 258K miles of faithful service (try that with a F*rd), and it suffered some broken radiator mounts.

The coolant system is a *closed* system, so yes, the t-stat seal needs to be watertight.

Sorry for the flame noob, but if you really want our help, give us more info and drop the "buy a F*rd" crap

 

I guess i haven't posted enough yet here for you'all to know my sense of humor! yea, the Ford line was certainly a joke! I would have to be mighty desperate before I would ever go down the ford road (or any domestic for that mater)...

what other kind of info would be helpful?

 

Cool. There wasn't a after that statement and believe it or not, people actually say silly stuff like that...

Try assembling everything without the thermostat. Don't leave it like that for long, but warm it up and see if it still overheats. If it does, we know the thermostat is not the problem and we can move onto other things.

 

I just want to know how you didn't 1) Notice the temp gauge was pegged and 2) notice the hellacious noise it must have made when the fan mangled your radiator... With that said it really sucks that all that happened. Hopefully your engine is not done. Have you tried flushing the coolant system yet? If the fan made it through one of the cores you may have ingested some junk into the coolant system.

 

The original thermostat has a c shaped o-ring around it that should be saved to use on the new thermostat. This o-ring is also the gasket to seal the thermostst housing. The themostat spring assembly end should go into the engine or it won't open.
Its very difficult to get air out of the cooling system unless you remove the top cooling hose and fill there also.

 

One of the first things I would do is a compression test on the cylinders. If they are within 15-20 lbs of each other, chances are your head gasket is ok, otherwise you're in for a head job. Also, check to make sure the fan clutch is still operable after the radiator slammed into it. To dod a comp check, Take out the spark plugs, insert a comp checker into the sparkplug hole, and turn the key over and let the engine turn over about 4 times. Even if you need a head job, your yota is worth it

 

another thing that you can do is smell the exhuast...if it smells kinda syrupy like....well burned antifreze then it may do it, you also could have overheated it, and mabey you had a bad valve that when you did overheat it, finished burining itself off, that would make white smoke come out of the intake when running, and i would do that compression check if i were you, that way you know...and hey, while you do that you can always replace the spark plugs! birds with 1 stone!

later
wade
ps sorry to hear about the bad luck....

 

I would go with the idea of removing the thermostat and fire it up. Does the water circulate before overheating (water pump impeller gone)? It's usually pretty obvious when it's circulating through the radiator. Do the heater hoses get hot also (is the coolant circulating everywhere)? Occasionally, the engines will get an air blockage that can cause a problem, filling through the top hose connection to the engine often helps there. There are cases where an engine will overheat with the thermostat removed because the water is circulating too fast, but that typically takes awhile. Another thought, the thermostat on my truck had a pin that MUST be installed at the highest point (assume to bleed the air out). Check your manual.

 

Thank you all for the ideas of where to start. Here is where I am at thus far...

Since replacing the thermostat, I have had a persistent leak around the thermostat housing somewhere. Gosh, I have had that thing off and on a dozens times now, and can't seem to see what the deal is. The housing does not appear cracked, the hose is not cracked, the hose clamp is good and tight and yet when I put it all back together, it drips quite heavily, ugh! I have tried it with the new t-stat & new gasket, using the old t-stat & old gasket, even now with no t-stat and no gasket and it is all the same leak.

Anyone have any ideas of what could be leaking? I don't see many more options down there! All I can see is a steady stream of coolant dripping from the edge of the oil pan, I cannot trace it up from where it is coming from because it is not obvious or I am an idiot! But, I sure hope it's not coming from the oil pan or I am really screwed!!

I tried removing the thermostat, and put it all back together. I still have my leak around that area, ugh! I ran the truck for as long as it would of taken normally to overheat and it did not, so that is a good sign. The coolant is circulating, as the hoses and such are all toasty hot. I want to try to get a handle on this leak and then run it longer to get a better since of the overheating issue. The engine still runs beautifully, and sounds great!

Thanks you'all for the tips and ideas!!

 

When I was doing my timing belt, I removed the water pump and T-stat to make sure both looked OK. Anyway, when I put it back together I used some black Toyota sealant. Sorry, can't remeber the part number or name, but its the same stuff used to seal the radiator hose to the outlet in the upper idler pulley on the 3.0L. Also didn't use a gasket. Just thoroughly cleaned both mating surfaces, applied the sealant, and bolted it back together. The sealant was like $12 at my local dealer and is made for sealing coolant passages.

Also, make sure the bolts that hold the T-stat cover on or going in all the way. You may need to clean out the bolt hole (probalby not, but something to check anyway).

 

Try this link: page 14

http://www.net-impress.com/4runner/cd/TROUBLE_.PDF

I think there was a gasket with a groove on the inside. The edge of the thermostat sets inside the grove of this gasket to seal the outside and inside surfaces it was mating to.

good luck

 

OK first of all make sure the housing does not have a crack in it. Next make sure both surfaces have been thoroughly cleaned (ie no gasket material left)...should see bare metal. When you install the new thermostat, make sure the hole in the thermostat faces up within 15 degrees (or you may get air in the system whch makes the car look like it is overheating). There should be no reason for extra sealer if the surfaces are flat and clean but if they got damaged somehow, you may need some to ensure a good seal.

Good luck with it!

 

...Stream of water along the oil pan?
There is a coolant hose that runs right along the engine block, on the drivers side, just above where the oil pan mounts. I think it goes to the rear heater?
Just a thought...

 

that is absolutely incorrect, a compression test can give you false hope!

 

In case anyone is curious here is how things turned out with my overheating 4Runner. I could never get the thermostat to seal properly. A huge thanks to forum user DarylD, as his keen eye led him to suspect a crack in the thermostat housing. Sure enough, there was a crack. With a tight seal around there, my overheating problems are no more and there seems to be no big damage from the overheating incident. Life is good once more and now I keep one eye on the temp gauge!

Thanks you all for the helpful insight!

 

Darryl RULES!

 

Does any one know if the thermostat housing on an '89 V6 3VZE engine is part of the block or seperate.....Have bad leak after replacing thermo & seal, hoses & radiator....
note* leak is not between thermostat and cover with the hose attachment*doesn't overheat*system was flushed*