92 PREVIA HELP -STILL OVERHEATING (new water pump, tstat, radiator, cat con) - Toyota Nation Forum : Toyota Car and Truck Forums
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#1 Old 10-04-2009, 02:21 PM
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92 PREVIA HELP -STILL OVERHEATING (new water pump, tstat, radiator, cat con)

GREETINGS.
NEED HELP SLEUTHING 92 PREVIA OVERHEAT ISSUE.

1) First overheat May 09. Mechanic says add fluid, watch for leaks.
Added fluid, all well until...

2) Second overheat early July 09. Had been no visible leakage.
Added fluid again, all well until...

3) Third overheat late August 09. Again had been no visible leakage.
Added fluid, all well for only an hour on freeway (on a road trip) then...

4) CHECK ENGINE light came on.
Van running extremely rough.
Near stalling at stop lights when we arrived at destination.
Per mechanic, try to drive it home.
Drove the 120 miles home.
By accelerate/release entire way.
If holding gas steady, extremely rough became shaking, shuddering.
Ran smooth on acceleration, so accelerate/release all the way home.
No overheating, plenty of fluid upon arrival home.

5) Mechanic checked code.
He did not tell me exactly what reading was, but said start point was
Checking Spark Plug wires.
Checked them and found one to be bad, blackened.
Replaced set.
All well until...

6) Fourth overheat mid September.
Added fluid, all well until...

7) Fifth overheat two days later.
Added fluid, all well until...

6) Sixth overheat two days later.
Added fluid, all well until...

7) Seventh overheat with NO INDICATION from TEMP GAUGE.
Running rough, even a bit of knocking sound.
A sweet kind of smell coming in.
Gauge reading fine.
Car dies at stoplight.
Park it.
Boiling over.
Let it cool down.
Added fluid, made it back home.

8) REPLACED WATER PUMP, THERMOSTAT.
Also REPLACED CAP/ROTOR as discovered to be melted.
Mechanic says bad catalytic converter caused too much heat in exhaust pipe caused it. Heard a rattle at reving when idling
presumably coming from cat con.
Test drove to Autozone for new radiator cap about a 5 mile drive.
Gauge reading fine.
Take off lid.
Fluid boiling.

9) Two more short drives less than 5 miles.
Gauge reading fine.
Double check at arrival.
Fluid boiling.

10) Mechanic comes back.
Use bleed screw to double check for air pockets.
Still running hot.
REPLACED RADIATOR.
Test drive.
Gauge reading fine.
Fluid boiling.

11) REPLACED CATALYTIC CONVERTER.
Mechanic suggests heat from it may be contributing to cooling system
overheat issue.
Drive home from repair about 15 miles.
Gauge reading fine.
Fluid boiling.

12) Had another mechanic suggest air pocket.
Tried bleeding it again with the radiator hose off and pouring liquid in it
at same time.
Gauge reading fine actually a bit lower down.
Fluid near boiling.
Not actual bubbling this time, just steaming out.

13) Another drive of about 10 miles round trip.
Gauge again reading a bit lower than previous fine readings.
Fluid again near boiling.

14) So $600, four repairs in and still running over hot.\
Second mechanic suggests cutting the middle out of the tstat?
Posting here to see if anyone has insight.

MANY THANKS.

Last edited by previainfo; 10-04-2009 at 02:28 PM.
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#2 Old 10-04-2009, 06:34 PM
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woah WOAH WOAH WOAH !!!! WTF. how many mechanics did u have to go tru and not find the f-king problem. these guys are fucking jokes they're obviously making money off ya.

1)ok, did any of these mechanics did a compression test? - the rough idling, rough acceleration is caused by a damaged knock sensor, when your engine overheated, the knock sensor got damaged. thats why it runs funny. and the knock sensor is only accessible if you drop the engine.

2) the rotor/cap melted cuz the head got so f-king hot - obviously the head gasket is done - - ps. the waterpump on the previas can go a long way, i didn't have to replace my Original waterpump on one of my vans ( i have 7 ) and it was at 450 000 km. (it has 500 000+km right now)

3) find one mechanic that knows these minivans. cuz honestly. these minivans aren't common to be found in a garage. they're heavy duty workhorses. thats why not many mechanics knows how these babies tick.

4) it pisses me off that you went to so many mechanics and not found the f-king problem.

5) second mechanic suggest cutting the middle out of the thermostat??!!?! (ok i've seen butcher work before. but did u just mentioned thats a new thermostat?)

6) i can't believe you replaced so many things. and not fix the problem. MY GOD !

Keep me informed, .

Last edited by awtomakina; 10-04-2009 at 06:36 PM.
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#3 Old 10-06-2009, 10:58 AM
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Thanks for responding. Still working on a resolution.

0) Van continues to run hot. Temp gauge goes up to almost middle.
Stays there. Previous to problem stayed at very bottom of icon.
Upon return from a drive (doing only 5 to 10 mile A to B trips),
at removal of cap there is an initial boiling over and then steaming
fluid, obvious near overheating smell. An improvement from the rolling
boil of the fluid in tank before but still overhot. Seems likely would be
rolling boil if driven a longer distance. Concerned about effects
of continuing to drive with it running hot. Should I take this elevation as
the new operating temp?

1) No compression test done as mechanic thought check engine problem
was made obvious when spark plug wires visibly showed to be bad. He
said we change these and everything will be fine. Which was true until
the overheating changed from a few times that resolved to ever
present.

2) The cap is right next to a y type of exhaust pipe juncture and the rattle
at idle rev did seem to be coming out of the cat con. So, from this
view it made sense that the heat there may have caused the melt?
However, he said the cat con would be glowing red when I checked it
and it wasn't.

3) When the new cat con was put on it was tested to be 3/4 blocked.
Also determined the rattle was not coming from the cat con, but from
a different juncture of the exhaust pipe more in the middle. Per these
guys was not any problem contributing to overheat, just a harmless
rattle of exhaust pipe. They confirmed that heat from the blocked
cat con may have caused the cap melting.

4) He ruled out head gasket because there was zero white exhaust smoke,
no white anything on the oil lid or when checking it with dipstick. Engine
also sounded good.

5) What are symptoms of a bad knock sensor? After spark plug wire
change everything smoothed out until overheat issue.

6) Is there anyway to test new thermostat? That was why butcher
work on it was suggested. If there was an air pocket, that mechanic
said only steam would get to tstat and it wouldn't open. Cutting it
would guarantee circulation of fluid, "this is how they run race cars."

7) First mechanic has done his best to figure it out over several years of
nothing major going wrong. He has done the basics alright. I guess it
would feel more honest it he said, "I don't really know on this one. Let's
not throw money at it." But the things fixed seemed logical, no?

8) The water pump was replaced first as water was POURING out of it and
it seemed the obvious problem until it didn't fix the problem. Tstat
added as already there and not expensive so makes sense.

9) Unless it did do some kind of fixing and there is just a new higher
operating temperature? Wishful thinking? What about out of town
travel then?

10) It just seems wrong for it to boil over a moment and be steaming. Sigh.
What next? Not sure what to do at this point. 185,000 miles and was
running beautifully until this started. How to complete it?

Thanks again.
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#4 Old 10-06-2009, 06:47 PM
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thanks for the info bud.

1st step.
COMPRESSION TEST - if OKAY (110 PSI + ) - DRY TEST. REMOVE FUEL PUMP RELAY (or EFI FUSE)

2nd step
Check COOLANT /ANTIFREEZE . Use an antifreeze tester. it should be in at least -40 celcious (not sure what kind u guys use down there) some coolant mixture that is poor can cause the integrity of the coolant, hence steaming?

3rd step. log back in there and tell us how 1st and 2nd went.


KNOCK SENSOR testing - if you need to back probe the ECM connector under the seat, not sure which wire it is. but if u can get a hold of a wiring diagrams for this, then it will help u out. check for voltage (if using a MULTIMETER. put it on voltage lol (V).

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#5 Old 10-07-2009, 10:51 AM
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Since you have covered plenty of bases, here is another "wild goose" to chase.

Could there be accumulated gunk, like "stop leak," in the engine block preventing sufficient cooling?


1995 Previa DX
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#6 Old 10-10-2009, 07:51 AM
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Thanks again for your help with this. Busy week, so drove hot. Hope to get to compression/fluid tests here next days.

No stop leak gratefully. Mechanic suggested it yesterday as last ditch wondering if there is a no symptom leak in the head gasket causing the continued running hot.

Told him I had some suggestions from here to check out first. I have heard stop leak is a bad idea. He said he has seen it work in some cases.

Will be back with results of tests, update as soon as time allows. Enjoy the weekend....
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#7 Old 10-23-2009, 08:57 PM
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NAPA sells a kit to check for the presence of exhaust in the coolant. Do a compression test. Get a new mechanic when you find what I think you will find.

This wreaks of a blown head gasket.

If you continually have a problem with one cylinder and the compression test and the test for exhaust in the coolant comes up clean then it is time to check the injectors if you find no other problems though I really think you have a combustion leak into the coolant system. Coolant is at 14-18psi but it may not be enough to push coolant into the cyclinder. The explosion when the cyclinder fires is at several hundred PSI and can blow combustion gasses into the coolant if the HG fails.

Most places that work on Diesels can get injectors cleaned and flow tested. Usually around $20-25 and injector and in most cases they can save the injector. If you have to remove the head I highly recommend doing this.

I have not personally used this place but their site seem on the up and up and the prices in line with what I have paid.

http://injector-rehab.com

Had this done on my 4Runner when I rebuilt it. 2 injectors had restricted flow and all had atomization issues with 200k on the motor. That motor runs smooth as glass now between the injector cleaning and having the motor balanced. it will idle smooth at 400 rpm if I crank down on it and it has a cam in it that is not stock.

Here is how I learned about this:

I had an issue where I had ONE injector go lean and burn the valves on my 89 Supra. Never threw a code but would boil the coolant around that cylinder and make it run warm. The ECM was able to dump enough extra fuel in the other cylinders to hide the problem from the O2sensor.

Regularly inspect plugs on any high mile motor. If they all do not look close to the same you have something going on. On my supra the plug in the cylinder then went lean was always showing different. I was too dumb to figure it out until I burned the valves and lost compression in that cylinder.

Running wet in one cylinder will cause lubrication issues AND the ECM will lean the other cylinders out trying to get a good reading at the O2. Wet cylinder can cause lubrication issues, crack rings and score cylinders.

Let us know what you find and complete the thread with the final resolution.

Last edited by Grim Reaper; 10-23-2009 at 09:01 PM.
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#8 Old 11-17-2009, 12:40 PM
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Perhaps head gasket...

1995 LE S/C with Dual Roof and Captain Chairs
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#9 Old 11-09-2010, 09:12 PM
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A year later

Apologize time to post outcome of this overheating problem evaporated in the heat of that challenge. I did get the compression test back then which was good. It still tests good now with new fuel rail issue gratefully.

I did also get a diagnosis of EXHAUST GAS IN THE COOLING SYSTEM. It was also back at this time, mid-October last year.

The estimate to drain the block and for head repair (said the cylinder was warped) was $1860 and not recommended as it is now a high mileage engine that had suffered a major overheat due to the gauge not reading it the one time it overheated all the way to sweet smell.

The other suggestion was coolant additive to assist in resealing the head gasket to see if that would work. Back to Alumaseal ...

AND It appeared to be assisted into the proper channels by the Gods as all was well and we've been driving smooth for almost another year. No long distance road trips, but in town driving needs met.

Wasn't until end of August that we started having a performance problem that was unrelated to this....

Other post has current mechanic's description of problem as being a corroded fuel rail. Hoping to find one as sinking in over $1000 with the known head issues doesn't seem genius. Hoping to get another year out of it if we can or at least long enough to gather what's needed to look for a new well cared, lower mileage Previa.

Thanks again for the great advice. I am going to print this thread and pass it on to current Mechanic as it could help future Previa or other Toyota owners. Hope to hear from someone on the fuel rail search.
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#10 Old 11-10-2010, 06:34 AM
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Quote:
Originally Posted by previainfo View Post
Apologize time to post outcome of this overheating problem evaporated in the heat of that challenge. I did get the compression test back then which was good. It still tests good now with new fuel rail issue gratefully.

I did also get a diagnosis of EXHAUST GAS IN THE COOLING SYSTEM. It was also back at this time, mid-October last year.

The estimate to drain the block and for head repair (said the cylinder was warped) was $1860 and not recommended as it is now a high mileage engine that had suffered a major overheat due to the gauge not reading it the one time it overheated all the way to sweet smell.

The other suggestion was coolant additive to assist in resealing the head gasket to see if that would work. Back to Alumaseal ...

AND It appeared to be assisted into the proper channels by the Gods as all was well and we've been driving smooth for almost another year. No long distance road trips, but in town driving needs met.

Wasn't until end of August that we started having a performance problem that was unrelated to this....

Other post has current mechanic's description of problem as being a corroded fuel rail. Hoping to find one as sinking in over $1000 with the known head issues doesn't seem genius. Hoping to get another year out of it if we can or at least long enough to gather what's needed to look for a new well cared, lower mileage Previa.

Thanks again for the great advice. I am going to print this thread and pass it on to current Mechanic as it could help future Previa or other Toyota owners. Hope to hear from someone on the fuel rail search.
I'm sorry...I don't speak French. Did you get the problem fixed or not? What was the problem? What was the fix?

When In Doubt...Charge!
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