jjrbus

1990 Toyota 6 cylinder 3.0 3VZE-E Automatic Transmission, Dully Winnebago Motorhome with 51 K miles. Problem started with Overheating under any condition. We bought this 1,000 miles ago.

Now it only overheats when going uphill with the air conditioning on.
It is overheating! Boiling and steaming. It’s not just the gauge saying it’s hot.
The heater works good and the air conditioning is very cold.
Had it weighed and its not over weight.
This is what we have done so far.
Replaced rear brakes and drums.
Replaced thermostat(s) 4 times (now have a Toyota thermostat installed). All 4 thermostat’s boil tested as good.
Replaced Radiator Cap twice.
Replaced Radiator Have a Spectra Premium CU1190 Complete Radiator for Toyota Pickup http://smile.amazon.com/Spectra-Prem...eywords=cu1190

Replaced Radiator hoses.
Flushed system twice – Used pressurized system to test and refill
Removed the Fan and Fan Clutch and replaced with electric fan, installed a Flex-a-lite 674 S-blade Engine Cooling Fan with Controls http://smile.amazon.com/gp/product/B...ilpage_o02_s00
The fan is blowing (sucking) correctly.

Removed and reinstalled new Water Pump (AISIN)
New timing belt installed. http://smile.amazon.com/gp/product/B...ilpage_o01_s02

Pressure checked coolant system no leaks.
Combustible gas (blue dye) test - no gas - passed
Compression Test 170 on 5 cylinders , 155 on one cylinder
Leak down test at 100 psi (twice) - no leaks detected.

Toyota Dealership R&R Head Gaskets via the Special Service Campaign
New Plugs, New Wires
Replaced Valve seals and adjusted valves. Copy of the repair bills http://imgur.com/a/ccKwY

Dealership just did a full check on the coolant system, pressure check, computer diagnosis all were good. They did a test drive and it is still overheating with the air conditioner on and going uphill.

The dealership says I should replace the radiator, electric fan, and fan shroud with OM parts. My question is why? The truck runs great at highway speed with the air on. Runs great in stop and go traffic around town with the air on. It idles fine and the electric fan is on all the time if the air is on.
It recovers very quickly when you turn around and go downhill. It will raise in temperature slightly if going uphill with-out the air conditioning on.

Suggestions so far are fuel filter maybe is freaky and only malfunctions going uphill causing the truck to run lean and hot?

Blow out the air conditioning condenser at the car wash.

Check to make sure the airflow is going through the radiator and not around the radiator. Use insulation to fill any gaps.

Ecu can go bad, O2 sensors can lie, and several other things can cause the ecu to lean out your fuel mixture. Lean =hot.

Suggestions?
Any HELP?

Kiroshu

Have you tried using a higher grade fuel? It does help with cylinder temperature under heavy load. Is EGR still equipped? This also helps with cylinder temperature.

3VZs are always a red flag for head leakage xD hopefully not in your case.

Have you tried running with the correct fan clutch? Fan clutches do better at removing more heat under loads and at slower speeds than electric fans. At least in my opinion haha. That kind of truck probably has a special towing package fan clutch.

Fans with shroud is important!

Seems like you have been covering most bases very well, sucks that you have this problem hope it is solved soon ^_^.

Is there anything on the front of the truck that could be restricting air flow to the radiator?

Janos01

The stock radiator fan for the 3vz-e blows more than enough air to cool the car. It is possible the electronic fan is not blowing as much air vs the stock one when going up hill. Have you changed your Air filter out regularly?

It is also possible that your radiator is defective as I have a similar one that I got from OReilly's.

I do not think you ECU is bad as those are a rare occurrence when it does go out. Mine is 26 years old on my 90 4runner and all I have is a EGR code but nothing serious.

As long as all your warning and indicator lights come on when you turn the key to pre-start and go away when you start the car, that is a diagnostic letting you know that those indicators are working.

wyoming9

iTrader: (1)

Like I said going up hill the engine the transmission and the condenser are all dumping heat into the cooling system

What kind of rpm if this was a manual transmission I would say drop a gear increase the rpm.

Is it possible your lugging the engine allowing the rpm to drop to low before the transmission down shifts ??

Condenser so full of dirt it is blocking the air flow

I know you just bought this when was the last transmission service ?? The more over due for a fluid change the hotter things run >

Sherrie Myers

Nothing but the AC condenser and Trany Cooler, and the Truck Grill of course.

Sherrie Myers

The Trany is an Auto and seems to be ok, I try to keep the speed consistent to try to keep it from bouncing in and out of 4th, I washed out the AC condenser and only had a couple of bugs. We don't do off road. Had the Trany Fluid checked and inspected and seemed ok.

RJR

What is your engine rpm when going up hill? It should be above 3000, preferably around 3500. If it's less than that you need to force a downshift. If it's a long hill shift the transmission manually so it stays in a low enough gear and doesn't hunt back and forth.

I agree with going back to the stock fan. Mechanically driven fans are capable of more air movement, particularly at medium-high engine rpm, than any 12V electric fan.

wyoming9

iTrader: (1)

I have had nothing but trouble with electric fans!!

The thing is with DC motors in most cases as the system voltage drops so does the rpm of the fan.

jjrbus

Update. First I re posted original post for someone on another forum and do not have all detail.

Toyota was taken to known Toyota guru in Las Vegas. His opinion was radiator was too small and recommended a different radiator. This is the 4th new radiator in truck! Too make a long story short it did not work and truck overheated worse!

Sherrie with some ingenuity rigged up a temporary misting system for radiator and was able to drive vehicle without overheating. misting system was removed.

Next step was to remove trim piece under front bumper and stock grill. The system was drained and had red and green antifreeze in it that had not mixed? The system was flushed with distilled water and filled with distilled water and a bottle of wetter water, no antifreeze.

The test drive was a success, no overheating. Note all test drives were done in the same location at the same speed. Only difference was ambient temperature. Jim

Sherrie Myers

Sherrie Myers

10-18-2015 Success! Just finished a 100 mile test drive and NO OVERHEATING!
I fill confident the issue with overheating is resolved. In reviewing the problem this is what I believe to have happen.
These are the steps to correct the overheating problem on the Toyota Winnebago, as they were given to me. They should completed in order one at a time then if overheating persists continue to the next step. (I would add – Only after you confirm the step performed is 100% correct)
1. Check Coolant level – add coolant if low and re-check. If leaks are found repair leaks. Inspect that the Radiator, AC Condenser and Transmission fins are clean and not bent. ( Burp)
2. Replace Radiator cap. (The highest quality is not always the most expensive)
3. Replace Thermostat. ( I would add - always use the Toyota Thermostat and boil test prior to installation) (Burp)
4. Replace the radiator or clean – professionally flush- pressure test the radiator and system. If you have any doubts as to the condition of the radiator after being professionally cleaned then replace it. (I would add- be sure the new radiator is the proper radiator for the size of the vehicle. Just because it fits does not mean it is the correct radiator for the application) (Burp)
5. Check that the Fan Clutch, Fan and Shroud are working properly– Replace any part if there are any doubts. (Burp)
6. Replace the water pump. At the same time it makes sense to replace the timing belt. (Burp)
7. Last but the only thing left is the Head Gaskets. There are three diagnostic test for Head Gasket failure. (a) Combustible Gas in the radiator. (b) compression test (c) leak down test. If you replace the Head Gaskets (Burp).
Burp, Burp, Burp the system after any service to the coolant system. (always use the same coolant – never –never mix coolant colors)
So were did we go wrong, there were many things that made the repair to the Overheating more problematic.
#1 We assumed that the Previous owners installed the correct new radiator, they did not. We also assumed that our replacement radiator that we had installed and was a larger capacity radiator was large enough, it was not.
#2 We did not boil test the thermostat’s we purchased prior to installation. We tried to use aftermarket thermostats. It was evident after purchasing the Toyota thermostat that there is a difference.
#3 We purchased a Radiator Cap that had a pressure release lever on it. This lever on the new radiator cap leaked.
#4 We allowed the mechanic’s to put into the coolant system any coolant that they had available. We allowed the mechanic’s to mix coolants – including green coolant added to red coolant.
So in retrospect this is what I believe to have happened. The Winnie was purchased with an overheating problem. Upon replacement I believe that the Fan Clutch was not functioning properly, we received almost 2 mpg more after replacement. The Water Pump although not leaking was not functioning properly, after removal the bearing sounded to be rubbing. With the fan clutch and the water pump bad the vehicle overheated and the previous owners replaced the radiator with the least expensive one they could and then sold it to us.
We being neophytes to Toyota Winnebago’s we did not know about larger capacity radiators. With the fan clutch and the water pump being bad, even when we replaced them, we could not overcome the insufficient radiator and we continued to Overheat. When we finally did order and have installed a large 3 row – high performance radiator, the mechanic that installed it mixed the existing red coolant in the system with a green coolant he had in his shop. The mixing of coolants did not allow the new radiator to perform properly and we continued to overheat! OMG. I am just thankful that it is now fixed. I will run it with distilled water and Red Line Wetter Water for a while and then flush and flush and then add a Coolant / Antifreeze back into the system. But from now on I will require that mechanics only use coolant that I supply to them.

ZUK

iTrader: (1)

Sherrie-
I'm in agreement with Wyoming9 that electric fans suck and not in a good way. Pulling large volumes of air is what the oem fan clutch set-up is about. Did yours have a shroud? They need a shroud to be effective.


If it overheats come summertime I bet a fan clutch with a fully encompassing shroud fixes it.