91 VR4 overheating issue... kooky ...

[dudewith91vr4]

ange, i'm flushing this sucker for sure, thanks for the link!

box, i ran straight power to the fan (come to find out it's the condenser fan, not the radiator fan) bypassing the resistor and two temp sensors going into the radiator... and it works... would you say it's the resistor or the coolant temp switch for this fan going into the radiator? relays are good... i can pick up two fans from the salvage yard for 50 bones, should i pull the trigger? heh

thanks again guys!

[box]

One more time!

Check the resistance from pin 87 to ground.

[dudewith91vr4]

One more time!

ok Box, no reading from 87 of the low rad fan relay to ground, tried it with ignition off and in acc mode, no reading, the multimeter just reads "OL"... at least it's not LoL ... heh

i had the meter set to continuity, positive terminal to pin 87, negative terminal to engine ground, hopefully that was done right.

[box]

You've likely got a faulty resistor then. Check continuity from pin 87 to the fan resistor, you should get close to 0 ohms. Then check continuity from 87 to the other side of the resistor, it should have more resistance. If it's open circuited (OL reading), the resistor is faulty. You should have 0 ohms resistance from one side of the resistor to ground.

[dudewith91vr4]

folks ... new revelation: opened the radiator drain plug and liquid flowing out looked like 80% or more water
.... opened thermostat housing and liquid looked like 80% coolant ... again, i had a mechanic replace the water pump...

does this modify your conclusion re: the overheating issue? (other than don't use that mechanic again)

i'm thinking replace 23 year old radiator over flushing it, what do you guys think?

[anyonebutme]

something is plugged somewhere it seems. Could be thermostat failed closed, plugged radiator, or the water pump is a bum unit where the pump blades are spinning on the shaft freely.

[sergechronos]

folks ... new revelation: opened the radiator drain plug and liquid flowing out looked like 80% or more water
.... opened thermostat housing and liquid looked like 80% coolant ... again, i had a mechanic replace the water pump...

does this modify your conclusion re: the overheating issue? (other than don't use that mechanic again)

i'm thinking replace 23 year old radiator over flushing it, what do you guys think?

If you're going to pull it out to replace it, why not just fill it from the top and see how much comes out of the bottom? I still think you have an issue with the thermostat. You used a non-OEM water pump though, which can be iffy in reliability. Radiators don't have moving parts that can fail, it either develops leaks or ends up with blockages. Most blockages come from poor maintenance of the cooling system. The 1G radiators are VERY good and use a copper core, so I'd have a radiator shop clean and flush it before replacing it.

At this point, you might as well drain the system, pull the radiator out, and pull off your thermostat housing. You need to replace the small hose that was leaking anyhow, you can use this time to pull the thermostat and test it (cheap to replace it anyhow), see how the radiator is looking. If you have water in the radiator and coolant in the thermostat housing, you don't have it flowing between the two. Pretty much limits you to an obstruction before the radiator (blockage in the upper part of the radiator, upper radiator hose, thermostat housing, or the water pump) IMO.

[Ange]

If you're going to pull it out to replace it, why not just fill it from the top and see how much comes out of the bottom? I still think you have an issue with the thermostat. You used a non-OEM water pump though, which can be iffy in reliability. Radiators don't have moving parts that can fail, it either develops leaks or ends up with blockages. Most blockages come from poor maintenance of the cooling system. The 1G radiators are VERY good and use a copper core, so I'd have a radiator shop clean and flush it before replacing it.

At this point, you might as well drain the system, pull the radiator out, and pull off your thermostat housing. You need to replace the small hose that was leaking anyhow, you can use this time to pull the thermostat and test it (cheap to replace it anyhow), see how the radiator is looking. If you have water in the radiator and coolant in the thermostat housing, you don't have it flowing between the two. Pretty much limits you to an obstruction before the radiator (blockage in the upper part of the radiator, upper radiator hose, thermostat housing, or the water pump) IMO.

Copper radiators can also corrode pretty bad. Mine was totally rotten.

Imo replace your 23 y old radiator with new copper or alu one. I bought an alu for 100$ from ebay. No complaints on that radiator used it the last 2 years or so. So I'd go with alu again. It's lighter, doesn't corrode and does the job.

[dudewith91vr4]

wow... i really appreciate the shared experiences and feedback from everyone.. this is the best forum i've ever had the pleasure of being a part of. got the radiator in today, replacing it now, after i do the resistor test that box suggested... if that checks out, fixing hose, checking thermostat, reinstalling everything, giving it a go... if still overheating ... gotta be that cheap water pump. does the timing belt have to come off to change the water pump

[anyonebutme]

yes, timing belt comes off, so the engine would need re-timed. The chances of it being a water pump are pretty slim, so it's best to exhaust all other options first.