Transport Running Hot

[Captquegg]

The past few days it has been up in the 90's here in Chicago and the van's engine gauge says it is running hot when I'm driving city or idling. When the temp gets up there the transmission also revs a little higher before shifting.

At highway speed the gauge is pegged at where it always is when it's cooler and everything is fine. According to the gauge, the van normally runs at 168 degrees, but the last few days it goes up to about 224 degrees.

I checked the fuses and they are fine, the fans are both spinning at idle, but I'm not sure if they are kicking into high speed or not. Turning the air on or off doesn't seem to make a difference in the engine temp.

Any ideas? How can I tell if the fan's higher speed is kicking in? Thanks.

'98 Transport

[cdru]

How are you measuring the temp? Where did you get your 168 and 224 readings? I too have a 98 Trans Sport and comparing my scan tool readings with the guage, the scale is definitely not linear to the scale printed. Normal operating tempature is 195 degrees. This corresponds to approximately the first major mark at the "11 o'clock" position or so. From there on, each minor tick is about 3 degrees IIRC. If you tell me exactly which tick marks are, I can give you an idea as to what those values represent.

The fans will not kick on until approximately 220 degrees. At that point, they will start spinning on low speed. At 230 degrees or so, they will start spinning on high speed. Turning on the AC on should kick them onto high speed as well IF your system is properly charged. If it's not charged properly, then the fans may never kick on due lack of AC system pressure.

GregA in the Venture forum has [url=http://www.links-to-golf.com/van/engine-cooling-system.html]this[/url page that has more information as to how the system operates. If you understand the schematic, then tracing your system shouldn't be too difficult. There are numerous threads in the Venture, Trans Sport, Montana, and Silhouette forums on the radiator fans.

A couple of things that you can easily check and/or replace for fairly cheap is the condition of the coolant, radiator cap, and temp sensor. If the coolant looks goopy, has a brown appearance, or has stuff floating/sticking to the side of the overflow, get it flushed out. The radiator cap can also be pressure checked to make sure it's working correclty. Finally, the sensor may start to go south, either reading hotter or colder then it really is. It's fairly easy to get to and costs less then $20. A little harder (ok quite a bit harder) is the t-stat. If indeed your coolant is only running at 168, it is stuck open and needs to be replaced.

I live in NE Indiana and have been having the same weather that you've been having lately. If your vehicle is moving, it shouldn't have trouble keeping around 195 or so. If it runs hotter then this, then it may indicate that there is a problem somewhere or at least your not getting the best performance out of your cooling system. At stop lights though, expect the temp guage to climb slightly, obviously more the longer you are sitting there without air flow.

The gauge should always move gradually though. If you have sudden swings either up or down, that is an indicator that you have a air bubble in the line. This can be a result of low coolant, a coolant leak, improperly bled system, or a head gasket failing.

[Captquegg]

<<Normal operating tempature is 195 degrees. This corresponds to approximately the first major mark at the "11 o'clock" position or so. From there on, each minor tick is about 3 degrees IIRC. If you tell me exactly which tick marks are, I can give you an idea as to what those values represent. >>


Sorry about that, I thought they were linear. It normally runs one small tick hotter then the 11:00 o'clock major mark. Lately, when ideling/city it goes up to one small tick hotter then the 12:00 o'clock major mark. What temps do those correspond with?

The radiator fluid looks fine, I had it flushed maybe 9 months ago. All of the temp changes are real gradual. Once I slow down though it is a pretty steady climb. When cold, my radiator fluid level stays at pretty much the exact same level in the overflow tank.

I recharged the AC myself last summer and it still blows very cold, so I would suspect those pressures are fine.

Thanks.

[cdru]

I'll check tonight with my scan tool to get the exact values. IIRC, the 1st tick after the 11 o'clock value was about 197 or 198 so it was running just a smidgen hotter then the opening tempature of the thermostat.