Thermostat Problems

[jfreelix]

My 91 164L has been running a bit warm the last few days so I parked it. Before driving it today I raised the hood to check fluids and found a small amount of antifreeze around the bronze/brass bolt head on top of the thermostat housing. I'm not sure what the purpose is for this bolt first of all. Does it sound like I just need a new thermostat? Do I use that same bolt on the new housing since they don't appear to come with one? Was it leaking around the bolt most likely because the sealant wasn't applied around the hole? Any help would be appreciated. Thanks.

[pavanbabut]

Quote:

Originally Posted by jfreelix My 91 164L has been running a bit warm the last few days so I parked it. Before driving it today I raised the hood to check fluids and found a small amount of antifreeze around the bronze/brass bolt head on top of the thermostat housing. I'm not sure what the purpose is for this bolt first of all. Does it sound like I just need a new thermostat? Do I use that same bolt on the new housing since they don't appear to come with one? Was it leaking around the bolt most likely because the sealant wasn't applied around the hole? Any help would be appreciated. Thanks.

[jfreelix]

Would this have any effect on operating temperatures going up?

[Craig]

Not really, and these thermostats tend to fail open which prevents the engine from reaching operating temp.

With the leak, do what Pavan said but anneal (soften) the copper washer by heating to cherry red and dumping it in a bucket of cold water.

[pavanbabut]

Quote:

Originally Posted by jfreelix Would this have any effect on operating temperatures going up?

[jfreelix]

I see. The temp goes straight to operating and stays there unless I'm driving slow or letting it idle, then the temp climbs to about the 200-210 range and returns to normal with faster driving. One thing is, when it gets hot I hear the fan really kick in but I don't notice it before...Alfista Steve just let me in on the fact that these things have a lower spped as well. I'm going to check that tomorrow. Hey, if the copper washer is missing, where do I get another? Is it something I can get at a hardware store? And is it the softness of the copper that forms the seal not neccessarily the diameter? Thanks all.

[pavanbabut]

Quote:

Originally Posted by jfreelix I see. The temp goes straight to operating and stays there unless I'm driving slow or letting it idle, then the temp climbs to about the 200-210 range and returns to normal with faster driving. One thing is, when it gets hot I hear the fan really kick in but I don't notice it before...Alfista Steve just let me in on the fact that these things have a lower spped as well. I'm going to check that tomorrow. Hey, if the copper washer is missing, where do I get another? Is it something I can get at a hardware store? And is it the softness of the copper that forms the seal not neccessarily the diameter? Thanks all.

[jontg428]

210-212 is normal for these cars when in traffic, I had mine go to 225 and then I called Jason at Alfissimo to get a new sensor. Luckily I was in town and we installed it and not my high speed fan comes on at around 195 or so, cheap insurance when driving in the desert.

[jfreelix]

I think my low speed fan resistor is bad and the crush washer below the thermostat bleeder screw is leaking ever so slightly. I have been told, correct me if I'm misinformed, that if pressure isn't maintained in the cooling system that it can lead to many problems including higher temps and a rough idle(which I had today for the first time). I did see some new switches available that will change the temp at which the fan engages, if this doesn't fix my problem I will try that next. You wouldn't know if these copper crush washers are at local car parts stores would you? Thanks all.

[Alfisto Steve]

Quote:

Originally Posted by jfreelix I think my low speed fan resistor is bad and the crush washer below the thermostat bleeder screw is leaking ever so slightly. I have been told, correct me if I'm misinformed, that if pressure isn't maintained in the cooling system that it can lead to many problems including higher temps and a rough idle(which I had today for the first time). I did see some new switches available that will change the temp at which the fan engages, if this doesn't fix my problem I will try that next. You wouldn't know if these copper crush washers are at local car parts stores would you? Thanks all.

[jfreelix]

OK, the fan is working properly at both low and high speeds. The bleeder plug is no longer leaking, for some reason. I ordered a new one just in case from International Auto Parts. They said I could get the crush washer from any parts store, is that right? The temp is still getting up around 212-215 range and it has been a fairly cool 60's and 70's. It does cool back down to about the 185 I'm used to once I get up to around 50mph for a while. The water pump was replaced by PO about 15,000 miles ago. I'm going to check the coolant to make sure it is a good mix but I don't know what to do after that. Is this just normal on these cars? Thanks.

[Alfisto Steve]

212.5F is defined as second tick mark above 175. Running there or below that mark in traffic is OK as long as fan works correctly.

210F is optimum for modern day vehicles.

Since thermal switch in radiator works between 198F Low and 206 +/- 3 High and it is a long way from thermostat and temp sender engine will run about 210 in traffic and maybe a little cooler on highway about 193F first tick mark past 175.

[jfreelix]

Good deal. I appreciate everyone's help. That's a real load off, Steve. I was just worried since it hadn't risen to that temperature in the first month I've owned it.

[Alfisto Steve]

Quote:

Originally Posted by jfreelix Good deal. I appreciate everyone's help. That's a real load off, Steve. I was just worried since it hadn't risen to that temperature in the first month I've owned it.

[jfreelix]

I will, Thanks alot Steve.