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View Full Version : overheating only at idle 2001 X-5 lt-1


badrad187
06-13-2009, 02:49 AM
ive put in new impeller and thermostat,blown out oil cooler and still no luck.its fine when the rpms r up but if i idle it pegs 240 very fast. any ideas?

thanks,
badrad

babymoore3
06-13-2009, 07:53 AM
If you are not overheating while moving that implies that force on the water system improves flow in the engine. Seems like a restriction somewhere... or system malfunction (gauge or wiring maybe)... Is your engine jacket water pump belt driven? Did you remove and check all hoses? Do you have infrared thermometer to shoot the temp at the coolant sensor?

Can you put the boat on a trailer? Pull the incoming hose off at the fresh water pump and back flush to through the trans cooler and out the intake of the boat. If this works get a fake-a-lake and pull the incoming hose on the exhaust manifold to verify you have water flow (do this for only a short time)?

JimN
06-13-2009, 09:43 AM
ive put in new impeller and thermostat,blown out oil cooler and still no luck.its fine when the rpms r up but if i idle it pegs 240 very fast. any ideas?

thanks,
badrad

Did you replace the water circulating pump? If you did and you used a regular one for GM, it won't work because the LT-1 has reverse cooling. Also, you mention that you replaced the thermostat, but your motor has two of them. You should have thin hoses to the exhaust manifolds- those are bleeder lines and you should make sure they aren't clogged.

Run it (just in the water, you don't need to take it out from the dock) and watch the temperature at idle. If it climbs, rev it up and see if the temp drops.

As I have posted many times before, I don't like the Fake-A-Lake, especially for this motor. Moving around in the boat when it's on the trailer makes it easy to dislodge the plunger cup and with some trailers, the bunks are in the way. I like an uninterruptable water supply when running a motor on a trailer.

badrad187
06-13-2009, 12:15 PM
two thermostats?did not know that theres the one on top in front wheres the other one? and yes if i rve it up it cools down but no clogging in the bleeders. im going wakeboarding today so i will take another look at every thing

badrad out

badrad187
06-13-2009, 12:23 PM
flushed everything no luck. its the motor not the gauge.
badrad

bigmac
06-13-2009, 12:45 PM
The LT-1 is problematic from a cooling standpoint...at least there are certainly a lot of posts on overheat problems with that engine.

It uses two thermostats - the upper one you found and should be a 160 stat. The lower one, also in front, is a 142 degree thermostat, according to the manual. Apparently you can't use automotive thermostats, must use ones designed for this marine motor - upper one has to be drilled for bypass.

At this point, I guess I'd replace them and see if that fixes the problem.

SkiDim has them http://www.skidim.com/products.asp?dept=1091 . Don't forget the O-ring - there is no gasket.