[jeffb99tx]

At least I hope. My car has not technically overheated, but when it gets to a little bit above 200 degrees, it starts releasing radiator fluid via the overflow tube. It has gotten to the point that I cannot take the car out if there is a chance of being in a long line of stopped cars along the highway or through town. After many checks with my mechanic including multiple resistor checks, replacing radiator fan bearings, cleaning contacts, system pressure checks, etc., the car was still doing its thing of not holding steady at 195 degrees.

My latest complaint was that the radiator fan appears to cycle off at about 195 to 200 degrees. Something must be telling the fan to shut off at that high temperature. His latest idea was to deactivate the fan sensor that is at the bottom of the radiator (the "coolest" point) and install an adjustable aftermarket sensor near the top where the water enters the radiator from the engine. That would maybe turn the fan on sooner. He purchased an adjustable radiator fan switch that will do the job and the plan was to do the swap.

When I show up on Saturday to drop off the car, he shows me a page from the Centerline catalog where they sell an identical part. They state that "The radiator-fan thermoswitch for the 164 is set for 210°F, right on the edge of overheating. This is too close for comfort! Our adjustable thermoswitch will turn the fan on when you want, giving you a larger margin for safety. We suggest approximately 185°F."

Wow, that is exactly what was happening on my car. The fan was cutting out when the temperature was way too hot. I take it most cars have already had this taken care of? I have never heard of this fix and wanted to pass it along to others with LS's who may be having similar heating issues.

I will let you know how things turn out later on this week.

Thanks everyone and cheers,

Jeff
Dallas, Texas
1994 LS

 

[goats]

THeres a VW part

That installs bottom left(from the front) that is a direct replacement for the current fan temp sender that does exactly that -- turn on at 185F.

Jeff I think your system has another undiagnosed issue though. Either your overflow cap is bad (not holding pressure), or your radiator is clogged somewhat, your tstat is not opening enough (or maybe too much) and or your coolant mix is not close to 50/50, or some combo of the above. Unless there is a frank boil, the overflow cap should hold the pressure (assuming no head gasket issues). By releasing coolant without a boil, it seems that your cap spring and/or seal is weak -- as has happened to me 2 or 3 times in 164 ownership. That cap is a 14.7 psi cap -- so system should be plenty tight if that cap is working correctly.

Personally I would fix the current problem before I went to a lower temp switch, since the 24V engine is designed to run at 195-200 all day long I would not try to make it run cooler -- unless thats a last resort.

 

[jeffb99tx]

Hi Goats, I agree that there may be something else going on. I have brought up all of those items to my mechanic and he has checked everything. He pressurized the system and let it sit overnight and said there was no loss in pressure. Radiator is fairly new (2 to 3 years old I believe) and is not clogged. The fluid was recently changed and shows a good color. Don't know about the mixture ratio. I have a new overflow bottle and I believe it came with a new pressure cap. He has also checked the electronic resistors thinking it may be one of them that is failing when it heats up. He is going to replace the engine thermostat. It is just frustrating in that the radiator fan seems to shut off too soon and the car never really cools down. Head gasket failure? Could be but I hope not. Will report back on if this helps out. Thanks, Jeff

_____________________

"Jeff I think your system has another undiagnosed issue though. Either your overflow cap is bad (not holding pressure), or your radiator is clogged somewhat, your tstat is not opening enough (or maybe too much) and or your coolant mix is not close to 50/50, or some combo of the above. Unless there is a frank boil, the overflow cap should hold the pressure (assuming no head gasket issues). By releasing coolant without a boil, it seems that your cap spring and/or seal is weak -- as has happened to me 2 or 3 times in 164 ownership. That cap is a 14.7 psi cap -- so system should be plenty tight if that cap is working correctly.

Personally I would fix the current problem before I went to a lower temp switch, since the 24V engine is designed to run at 195-200 all day long I would not try to make it run cooler -- unless thats a last resort. "

 

[goats]

replace the overflow cap

would be the first suggestion -- or at least make sure that cap is pressure tested -- GOAT's (dont try this at home) overflow cap gross fail test-- remove it, rinse it under cold beer, and then try to suck on the overflow stub. If you can suck any air out (while holding the white piece hard against the cap) the relief poppet or gasket is bad. Have had one right out of the box that failed. As I say, unless there is BOIL in the tank, or elsewhere, that cap should hold tight, assuming no exhaust gasses are leaking into the cooling circuit. One other thing--- make sure that the entire system is purged of air, if there is a big air pocket, it will expand and increase pressure in the system. Use the bleed screw on top of Tstat housing.

I think you are on the right track with tstat replacement as a start here.

 

[75evo]

BTW, why do Japanese car run coller than the 164? The answer is they probably DON'T! The engine maybe at 205F but guess where the temp gauge is pointed to...you guess it, the 1/2 way mark. Verified this on my TSX and MPV with an OBD2 scanner and Raytek temp gun.

My guess is to get the engine to run efficiently it needs to run HOT. And the limit of the system is not far away from that point. So psychologically it would make "more sense" (ummm...ok) to say that "no problem your car is only 1/2 to overheating, when in actual fact it's about 20 degrees F away)

 

[goats]

jeff is this fixed

yet? summer is here and we dont want you overheating

 

[smotheredsteak]

someone said (t-stat may be open TOO MUCH??) i took my thermostat out and the car does as stated above (overheats over driving time) so putting a thermostat in to make the car warm up faster when you start it in the morning is supposed to help?

 

[Del]

The thermostat regulates the flow of the coolant through the block and head to ensure that there is proper heat transfer and thus proper cooling (when the rest of the system is up to snuff).

The cooling systems on just about all cars are designed to work properly when a thermostat is installed.

 

[smotheredsteak]

you would think that the t-stat limits flow a little.. just a little

 

[Del]

That's exactly what it does, as designed, when it regulates the flow. It's not suppose to allow maximum free flow as if it wasn't there at all. There has to be a varying amount of restriction, dependent on coolant temperature, at the end of the coolant passage layout to ensure that all of the various spaces in the block and head passages have enough coolant contact and exposure time, IE, a certain flow rate, not too fast, not too slow, to maximize the heat transfer to the coolant passing through.

It's designed to have a properly functioning thermostat.

 

[AlexGS]

Alfa V6 thermostat is a bypass design, meaning that when closed, coolant circulates around the engine due to a round hole (bypass passage) below the thermostat. When the thermostat opens, a spring-loaded disc closes off the bypass passage. If the thermostat is removed, there is nothing to close off the bypass and some of the coolant takes a shortcut through the bypass instead of through the radiator. That's mainly why it runs hotter with the thermostat removed.

Meanwhile, I find that when fan switches get old, they lose their hysteresis - that is, they turn on and then off again at more or less the same temperature instead of turning off about ten degrees lower than they turned on. This means the fan only runs for short bursts and isn't effective. I reckon a new fan switch might be worthwhile - but an adjustable fan switch is a good solution instead and probably cost about the same.

-Alex

 

[jeffb99tx]

Well, after a weekend of driving, the repairs and modification appears to have done the trick. I will post a photo of the new set up in a few days. The thermostat was replaced and the old one had signs of small grooves cut into the central shaft. It may have been sticking, but there is no way of knowing. The new adjustable radiator fan switch sits at the top left side of the radiator (if facing the front of the car). The heat sensor is actually inserted between the radiator fins and we positioned it along the top row over on the right side of the radiator. The mechanic tested it and the fan now comes on when the temp hits about 185 degrees. My car never got over 185 this weekend.

Overall I am very pleased. I do not believe the water temp inside the engine is cooler than it needs to be. Shouldn't the engine thermostat regulate engine coolant temperature to the desired temp? I just want to keep my radiator as cool as possible so that it does not hit 200 degrees in the full heat.

I would have done this sooner if I had known the factory setting for the radiator fan switch was set so high. I recommend this modification for all 24 valve owners in hot climates, as I do not know if the 12 valve cars have this overheating issue.

Thanks everyone,

Jeff
Dallas, Texas

 

[ChazzyD]

Modern day cars are supposed to run at 210 - 212*F for maximum fuel efficiency and lowest emissions and the 164 should be able to do the same. If it can't, than something has failed. If it works for you though in Texas heat to make these modifications, than that should be fine. If you have trouble passing an emissions test though, you might need to bring the temp back up a bit closer to the original design of the system.
Charles

 

[jeffb99tx]

Hi ChazzyD, your comments about engine temperature are interresting. I suspect the engine thermostat may have had a part in my overheating issues. The good news is that this new radiator fan relay is adjustable and we can set it to a higher temperature level if there are emmissions issues.

Regards,

Jeff

PS: are you going to the convention? I wish I could make it, but too much going on with my kids this time of the year.

 

[jeffb99tx]

Status update: it has been about six weeks and the temperature of the radiator has not gotten above 185 degrees. It has passed several stress test situations where I was stuck on a congested freeway for 20+ minutes trying to get past a wreck in 105 degree heat. The car did not get above 185. If anyone is still having issues with high radiator temps and has made sure all other parts of the cooling system are working, I would suggest this fix.

Cheers,

Jeff
Dallas, Texas
1994 LS

 

[Amphicar770]

Even if you set it for a higher temp, this seems like a worthwhile modification. Seems like it bypasses a lot of failure prone complexity.

 

[Richard2]

I had one of those adjustable switches on the 164B when I first bought it. It was very erratic. Sometimes worked, sometimes didn't. I eventually took it off and replaced the radiator switch and thermostat. The original system works better than the aftermarket ones. I suggest you watch it carefully as it ages. My guess is it won't work for long.