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Post by flyboy110b on Sept 13, 2010 19:22:14 GMT -5
Hey everyone! been a while since i've been on the forum, but i'm hoping you guys can give me some advice.
I have an 87 4runner, 22re efi with 188k on the engine.. its treated me fairly well so far, aside from an appearant overheating problem.
So when i bought the truck, it had the stock radiator fan in it, but no fan shroud.. seemed to overheat worse then. Since then I picked up an electric fan with shroud from a newer Ford Torus and fit it to my radiator (with a little modification) and took out the belt driven fan with the hopes that I'd gain slighty more power. So now, when I'm driving along on flat ground, it does great. but along comes a hill, and it slows way down, and starts to heat up.not to the point of boiling over the coolant, but still too hot. then cool once again on the downside.
So, what i've done to try and fix this is
Compression check (all within +/- 10psi of 175) Adjust the timing, Replaced the thermostat and water pump (both are aftermarket). The Pump pumps.. i know aftermarket thermostats arent the greatest, but I even took the old one and modified it to be open all the time, and it still got hot.
I've also ran a resistance test on the coolant temp. sensor. and after taking the temperate of the truck at operational temp (180f) the sensor seemed to fall within an acceptable range.
now here's the weird part.. if I unplug that sensor, the ecu will spit out an error code, as expected.. however, the temp gauage still reads "normal". I unplugged everything to do with temperature (coolant guage, temp switch, cold start timer) and the thing still showed normal..
so is this a problem with my guage? ecu? Will I have better luck with the stock fan and shroud rather than my electric? any advice will help
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Post by fourwd1 on Sept 13, 2010 20:17:37 GMT -5
The gauge and the ECM use different sensors.
As for overheating, you haven't addressed the 23 yr old radiator. The lower portion could be clogged and unable to the added load from driving uphill. Or it could be the elec fan is inadequate for the job. Or both.
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Post by whomadewho on Sept 13, 2010 22:00:49 GMT -5
The radiator would be a starting point.Was the radiator repaired before? Possible the radiator was leaking at some point in time and a few rows of cores where clipped. The thermostat can not be open all the time,it needs to open and close to allow the coolant to cool down. Check the radiator cap,a bad cap will cause overheating. You might have gotten a bad thermostat. Take the thermostat out,place it in a pan along with a thermometer,heat the water to check where it opens. Does not seem possible,but nothing is impossible, is the rotation of the fan correct? How many rows of cores does the ford radiator have?
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Post by flyboy110b on Sept 15, 2010 8:51:46 GMT -5
Ok.. well if there ECU and guage run off of two different sensors, where's the sensor for the guage.. my toyota service manual (not chiltons) says its rights under the outflow hose of the thermostat..
The rad cap is in good condition. no cracks or discoloration.. besides, if that was bad, i'd be loosing coolant which is not the case here.
I still have the stock rad in the truck.. perhaps it can be dipped, but i'm not sure where to take it for that.. I did run water through it, pressurized it with the garden hose.. it seems to flow freely. though last time i did a coolant flush, i didnt open the drain plugs on the engine.. maybe something's in there.. but I guess the only option i have right now is to get a fan shroud for that rad and throw the old fan back on.. My electric fan is supposed to be a two speed, though 2nd doesnt engage.. so maybe its okay on cold days or just to run around town with, but just not fast enough for freeway use.
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Post by whomadewho on Sept 15, 2010 13:29:29 GMT -5
The sensor that has a (GREEN) plug goes to the ECU. It is located below the by pass hose,or below the thermostat. The concern with the radiator cap is not only being bad or good, the pressure may be to high or low which can cause overheating. I think but I am not positive, the vehicle should have a 8 lbs. pressure cap. The problem is the vehicle was overheating before you changed out radiators,so its tough to isolate the problem and resolve the issue. Does the OEM have a clutch fan? Possible that without a shroud combined with a bad clutch this could cause overheating.
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Post by flyboy110b on Sept 16, 2010 21:45:25 GMT -5
Where can I have my rad cap tested? and I didnt change the radiator out, only the fan.. stock rad is still in and has always been. The orginal was a clutch fan.. that clutch was the first thing i tried.. at first I put in longer bolts in it so it would spin at regular engine rpm all the time.. but then i took it apart later and noticed that there wasnt much fluid in it.. so what instead of finding the silicone fluid that goes in, i just used some hydraulic fluid, and it actually did the trick quite well.. it cooled better.. with all the little things I've actually been make some progress. i read another tip in here that said a clogged cat converter can cause overheating.. so i took it off yesterday to inspect it.. altough the outside is dirty and rusty, inside is clean as a wistle.. guess that's why it smoggs so well  well.. I think i'm going to ebay a stock radiator fan.. perhaps see what a new rad will cost me. And i think while i'm at it I'm going to buy a new head gasget as well. Sometimes i notice a slight white coloration in the exhaust.. that's a sign of burnt oil or coolant? whatever the problem essentially is.. if i unplug those wires to the coolant sensors, that freakin guage shouldnt work at all. I've seen three, one on top of the thermostat with a single wire, and two below the hose both with two wire.. are there any others? |
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Post by whomadewho on Sept 17, 2010 21:28:33 GMT -5
The radiator cap can be tested at most parts stores or at a local garage. Before you purchase a new radiator, you may want to take the old radiator to a local body shop or radiator shop and have it serviced. The thermostat should be replaced if it is staying open. The vehicle came with a clutch fan,you may find a after market fan without a clutch (not sure where) Pull a spark plug,if you have a plug that is to hot this could cause overheating. Just an opinion,before I would replace the head gasket,I would have or do a leak down test. Price out the hourly labor at your local garage verses buying a tool to pressurize the cooling system,the tool is the same tool to check the radiator cap. You may be able to rent or borrow the gauge? To preform the test, remove the spark plugs,pressurize the cooling system (15-17lbs) if the pressure drops check for leaks(hoses heater core etc) let the vehicle sit for a while,have someone turn the vehicle over and note if any coolant comes out of the plug holes. If not install the plugs.start the engine and note if a mist or coolant comes out of the tail pipe. If either event occurs,this would not be a good thing. With the engine (COLD) remove the radiator cap - start the engine and let it get up to normal temp. check and see if any bubbles occur, this would also indicate a head or head gasket issue. As far as I know, there are not any more temp. sending units.
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