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View Full Version : Wedge TR7 temperature sending unit and cooling



johnrip
08-21-2009, 07:49 PM
I am reasonably sure that my dash temp gauge is working properly. After driving the car, the quage only reads a bit below half. My question is...how do I check that the sending unit is working properly. The engine is a new rebuild (lower)..and it seems to me that the head gets very hot, and is still hot 3 hours after the engine is turned off. Is that normal....Is the car running to hot and is the sedning unit accurate? If I groung the sending unit wire..the gauge goes full. Thanks

WedgeWorks
08-21-2009, 08:10 PM
The TR7s run between 1/4 and 1/2 typically. If you pull the lead on the temp sender and ground the gauge and it goes all the way to the right, hot then the gauge is working fine. The sender unit sometimes could use a cleaning if there is a bunch of junk/corrosion on the end of it. I have never seen a problem in TR7s or TR8s with the sender or the gauge with the exception of when you turn on the side and headlights then it might go up a little bit due to a voltage/grounding problem with the dash lighting. The head will stay hot for a longtime. That is just how aluminum is. Remeber to use never/anti sieze on the threads of the spark plugs to keep from damaging threads if you have to pull or put a spark plug back in when it is hot or warm. I dont any reason to worry. Looking for coolant leaks with a rebuilt engine, keeping the coolant filled and making sure there is no foaming oil are key to a TR7 after a rebuild.

johnrip
08-21-2009, 08:49 PM
Michael,
Great info, thanks so much. Just a question...foaming oil would like what? Do you mean oil leaks or how the oil looks on the dipstick? Thank you for the info...John Ps...if I were to check the sensor for corrosion...can I just remove it or it it under coolant pressure?

WedgeWorks
08-22-2009, 06:20 AM
When you pull the dip stick out you should have clear oil if not a bit dirty but to see a white/grey foam on it means you have a head gasket issue and coolant is getting into the oil. This occurs if the head was not plained/checked for warpage and installed and/or if the head was not properly torqued. This could even occur after it run too hot and warps the head. Just somehting to keep your eye in if coolant starts to disappear or you start running hit 3/4 on the gauge. Unfortunately you would need to drain the coolant to remove the sensor/clean and put the sensor back in. If you are running at the temperatures you are indicating you should have no worries. When you start loosing fluids and running at 3/4 or pegging the gauge you have a major problem. Did you install a new water pump in the bottom end rebuild?

tr8todd
08-22-2009, 08:40 AM
If you have a head gasket issue, you could get oil droplets floating in the expansion tank, and you could get the foamy mess stuck to the underside of your oil fill cap on the valve cover. On 7s and 8s, you have to burp the coolant system several times after you first fill it to get all of the air pockets out. This should be done very carefully so you don't get a face full of hot coolant. Any air pockets in the head can cause overheating and warping. Another rule of thumb for the 7s is to retorque the head bolts at every oil change. It ensures they are uniform in torque, and keeps them from seizing inside the cylinder head.

WedgeWorks
08-23-2009, 07:28 PM
tr8todd should know I think he has owned/parted out more TR7s then a typical dealer would have sold in the production run!