pplusent

I have a 93 4runner 3.0 with auto transmission 488 gears 4x4. On a recent post I noted that I installed a Tarsus fan and had just done an ac compressor. Well at 600 miles the compressor started intermittently locking up and spinning the compressor clutch. I was also burning out fan motors, three to be exact. Well the fan caused the engine to over heat three times. Since then I replaced the compressor again, the condenser, evaporator, TXV valve, receiver dryer and hoses on the ac, but it would not pull down to temp. Turned out the condenser was not the right one, so installed the original after flushing 8 times. Then still no cool, so replaced the TXV three times, the last time with the original. Turns out two of the txv valves were bad. Now I have it charged up and it pulls down to temp eventually but not the way it used too. There was a small mix up on the oil replacement when changing out parts and I think there may be too much oil. The compressor is dropping the engine rpm by 250 rpm which is a big load and the engine is heating up on the freeway to a 1/4 inch from red line, but returns to normal if ac is turned off. The engine has never run this hot in the past and the out side temp is only 104 degrees, it will get much hotter in the summer. I am reluctant to take more oil out of the ac system, but I am considering taking an oz out. I have had the brass three row radiator rotted out, re-cored and I changed out the t-stat and cap The overflow fills and drains normally. The water pump has 14000 miles since the engine overhaul and there is no fluid leakage from engine, no water in the oil and I am not burning antifreeze (plugs are normal). Also I have duel exhaust with no crossover behind the engine. I have changed over to the Thunderbird electric fan now which is a 19 in fan compared to the Taurus fan at 16 inch with the same motor, two speed controller, 120 amp alternator, a low speed fan sensor at 180, high speed at 200. The fans were burring out due to Toyotas small engine ground which has been changed to a #4 ground and alternator lines. The other problem that occurred at the same time is the engine off idle response. I go to a light and it responds normally, but then at the next light I have literally no engine response at all and have to floor it to get it to barely move until rpm get higher and then it responds. This started intermittently with the second compressor and the second overheat. Also not as bad when ac is off, but still have to put the peddle half way to move.
Seems to be three distinct problems. Anyone have any ideas?

pplusent

I swapped out the mass air valve today and the power loss off idle is much better. Still full power on acceleration is just not up to snuff. Checked resistance on the TPS and it is not functioning to spec. Will have new one on Saturday. I am also replacing the ECM, distributer and possibly the computer Saturday to see if one of these Items is over advancing the motor which would give me a power loss and possibly heat up the engine. If that doesn't do it I will remove an oz of oil from the AC system to see if the drag goes away and see if it starts cooling correctly.
Will update on Monday.

pplusent

I was testing the TPS and found no voltage at TPS. Then tried to put into diagnostic mode and it would not enter diagnostics. Checked the timing and it was not responding. The jumper to disengage the computers advance was not disengaging the advance and unplugging the TPS was not changing the way the engine was running. After testing with the voltmeter I must have grounded the computer because the voltage came back to the TPS and the diagnostics kicked in and I was able to check and set the timing. I believe the computer had gone into a safe mode, or limp home mode. Now the power has come back, plus, but, I seem to have a dead spot in the TPS between 2000 and 1500 when I level off on the throttle I see this because the RPM on the engine and tach bounces around in that RPM range. This may be what put the computer into safe mode! We will see if this is corrected by the new TPS when it gets here.
The temperature is much better, but I get a deviation after running hard on the freeway and when I get off the freeway and stop at a store, yet it comes down in a few miles. I think this is due to the blade design on the Thunderbird fan. The blades are much wider than the Taurus fan and may be acting as a restriction on the freeway. I have noticed on my cars with V8's in them the fan shrouds have cutouts in the shroud covered with a thin rubber strip. I believe this allows airflow around the fan when at high speeds allowing oncoming air to go around the fan. I may make some cut outs on this shroud to accommodate high air flow. The old Taurus fan shroud did not cover the entire radiator, Had smaller blades, and was a smaller diameter fan, so this was not needed and there was no cooling problem.
I also removed a half ounce of oil from the ac unit and the temps are pulling down much faster and it's dragging on the engine much less. I may need to remove another quarter oz. or so to get temps pulling down where they used too.
Will update when parts come in.

pplusent

It's been a bad week for the 4runner! Temperature problems constantly. Doesn't matter if I run the Tarus fan or the Thunderbird fan. Pulled the plugs again to see if the head gasket was leaking into the combustion chamber. Unfortunately, all the plugs insulators were extremely white. `Seems for some reason the engine seems to be running real lean! I changed the air metering valve two steps richer, but still hot and lacking power. I then checked the TPS setting and the timing. For some reason the timing had moved to TDC, so I set it at the usual 10 degrees. seems to slow down the overheating and power is back! Will recheck tomorrow and see it there is any color on the plugs. I can then check the cylinders with a bore-a-scope.
It may just be time to install a Chevy drive train.

pplusent

Ok. I have changed directions on this overheat problem. I was checking the spark plugs and noticed all the plugs are running extremely lean. Insulators are white with a touch of yellow on one side of the top of the insulator. All were the same except the number 6. had no deposits what so ever like it was washed clean. I assumed it was from coolant in the cylinder, but I am not losing any coolant. I started thinking about when overheating started. I had just put in the 4 hole injectors in the motor. I am thinking an air leak at one or more injectors/ fuel leak. I managed to get the temperature down by adjusting the air valve 5 clicks richer. The engine is now running stronger and smoother than ever, but still getting hot on occasion, so I an going to pull all the injectors and test for Ohm's and flow. For some reason the engine is forcing the mixture to lean out. Maybe the o2 sensor is giving an erroneous reading, or the fuel pump is week or filter clogged I don't know yet. I will check it all this weekend. What I do know is the lean mixture was part of the problem and it is going to hit 120 this week so I need it to be cool!

toiyodah4WD

Automatics run hotter, A/C taxes engine, and electric fans just don't keep engine as cool. I see 3 strikes right there. Why are you running an electric fan? Bad idea!!! If you do a search you'll see the pros and cons. It just won't keep the engine as cool --- as you've found out.

pplusent

The Taurus fan keeps it as cool as the clutch fan and better at idle. The problem with the fans is I keep burning out motors and I can't keep 12.5 volts at idle, I do have a 145 amp Att. With the clutch fan the engine will over heat if it has to idle for more than three minuet's and I lose all HP with the fan and A/C. The truck would be faster from a light if I got out and pushed. I believe the overheating is due to a fuel problem. The engine was real lean.. I'm checking that next week. The fans did all right last year in AZ heat. The trams is another source of heat, but several coolers keep the temp around 130 to 160 and never more than 160. I run a cooler in my AC duct and the tranny never gets hot. The fuel seems to be the issue. I believe might have a bad fuel injector or an air leak at an injector. Waiting on seals.

pplusent

Found one of the new fuel injectors staying open. The computer was compensating and ran mixture extremely lean. Replaced ll the injectors now engine running goo, but still overheating. Went back to clutch fan, still over heating. I have gone through cooling system and everything good. no coolant loss at all. No leaking, oil good no water, plugs still slightly lean but have some color. Water pump is the only thing I haven't changed. 14000 miles on the water pump.

L5wolvesf

Have you fully burped the system?

ksti

Lot going on here.
#6 sparkplug washed out, alot of times turns out to be bad head gasket.
I would do a leak down test or check for exhaust gases in coolant.
If your having to adjust the VAFM, there something else going on.
Hope you find out the problem.

thook

really? two threads?

millball

What is the general condition of the cooling system?? Has it ever been really rusty in the past?? Has it ever had any stop-leak type products used in it???

The head gaskets have several different smaller holes in them that are calibrated and designed to limit, and/or restrict coolant flow so as to equalize head temps.

When rust, corrosion, or scale plug, or restrict these smaller passages, there's gonna be trouble. Application of stop-leak products often causes the same trouble.

I absolutely agree that electric fans are not the way to go. A correct factory fan, fan clutch, and shroud can't be beat. Trust me, there's very few places in the US hotter than where I live and run my machines.

pplusent

Yes , several times. No bubbles coming up.

pplusent

The block has recently been boiled out when rebuild was done 14000 miles ago, only new coolant has been used. Block and heads decked with new nitroseal head gaskets. New water pump and T-stat. Radiator recently cored and cleaned out. running brass three row radiator. New rings, freshly ground crank etc. Rebuild AT, but did run hot, but now have three coolers on AT and maintains temps from 130 to 160 all the time and I don't use the radiator trans cooler..

pplusent

There are no signs of water in the oil , there is no excessive pressure in the radiator. no water loss, no smoke from the exhaust and when I pulled and checked fuel injectors the lean #6 wentt away and then #1 when extremely rich. Injector was stuck open. replaced all inflectors and plugs are now running normal, but still getting hot. And still running VAFM two clicks rich to get some color on the pliugs.

L5wolvesf

Not questioning your abilities but are you sure? There have been a number of posts here with similar symptoms and all else was new or cleaned. When they redid the burp the problem went away.
Often parking the truck on an significant incline will help a lot and let it run for a while.

ksti

Okay, have you done a simple radiator pressure test?
Also like I said, if you are adjusting the VAFM to compensate for overheating then you have another issue.

pplusent

Good news and bad. replaced the new radiator cap with a new Stant cap and replaced the new thermostat with a new Stant thermostat and the engine is now staying cool, at least on short drives. Will have to take a trip to see how it does.
Now I seem to have a backfire though the intake when I first start it in the morning. Back fires a few times then clears up. Maybe to much left over fuel from when it is shut off the day before, or it could be the new computer or the new ignition module or maybe a lean cylinder. Won't know on cylinder till I pull the plugs.. Timing is right on 10 BTDC. I have view ports I made in the timing belt cover so it can be checked on the fly and the marks are right on. so looking for vacuum issue because it is not charging the brake booster right away. It's fine after applying brakes a couple of times, so it is either not producing enough vacuum at start up , or could be a booster leak. I am starting to wonder if this vehicle will ever stop with the malfunctions.

pplusent

I went though all the vacuum lines and found when I folded the plenum back out of the way to get at the fuel injectors the brake booster line came loose just enough to leak. Tightened it back up and vacuum problem when away and I will bet so did the morning backfire problem. I think that was a lean misfire. Temp is staying right where it is supposed to and I still have some power even with the clutch fan on there! All good so far.
Thanks all. Sometimes it helps to have feed back to help troubleshoot when multiple things are going on.