Lee21490 Posted February 16, 2014 Share Posted February 16, 2014 Mk So couple of weird problems here. Noticed that everytime i let my truck idle within 10-30 seconds it climbs from just to the left of 210, to half way between 210 & the red mark If i give it 2-3k rpm it drops down almost instantly... Would this be a water pump? Faulty sensor/gauge? Idk Other thing is, Randomly my tail lights blew a fuse. Replaced it, now whenever i hit my brakes it turns on my Dash gauge lights. And if i turn on my headlights, it turns on my brake lights in the rear & makes the left blinker stay on the whole time, Right one works fine. Would that be the multi-function switch? '86 manche With 95 4.0L & Column/dash Any ideas would be appreciated Link to comment Share on other sites More sharing options...
Rockfrog Posted February 16, 2014 Share Posted February 16, 2014 Sounds like the fan clutch is failing ... when you gas it the air flow and water flow increases cooling the motor. if it was overheating all the time I would suspect the water pump, but tyou only notice it at idle ... when the only airflow comes from the fan. Link to comment Share on other sites More sharing options...
Lee21490 Posted February 16, 2014 Author Share Posted February 16, 2014 Sounds like the fan clutch is failing ... when you gas it the air flow and water flow increases cooling the motor. if it was overheating all the time I would suspect the water pump, but tyou only notice it at idle ... when the only airflow comes from the fan. Sorry should have added more detail. This is with the aux electric fan on, And the clutch on the mechanical fan was replaced a few months back. Thermostat was also replaced And radiator was flushed out the best i could with a garden hose. also does it at idle while coasting Link to comment Share on other sites More sharing options...
Rockfrog Posted February 16, 2014 Share Posted February 16, 2014 OK starting to sound like its time for a new pump then ... or a new rad. Link to comment Share on other sites More sharing options...
Lee21490 Posted February 16, 2014 Author Share Posted February 16, 2014 OK starting to sound like its time for a new pump then ... or a new rad. Yea, Thinking its the pump. Its done this minorly in the past year~, But got really bad today up in the mountain. The fluid looks clean, and is never low so i don't think it'd be the rad. No bends/crimps that i can see. Link to comment Share on other sites More sharing options...
Rockfrog Posted February 16, 2014 Share Posted February 16, 2014 When I did the rad in my 2000 XJ it all looked good. I just figured after 14 years it was time and I happened to have the spare cash (was $125 cdn which was less than I expected). Then I jammed the hose into the drain and plugged the outlet. Bounced form outlet to inlet and all of a sudden I got a rush of crap and rusty crud. Then it flowed like new again. Swapped the rad anyway and now that old stock one is in my MJ working fine now. Might be worth it to at least pull the rad and give it a good flushing ... it could just be paryially plugged. Link to comment Share on other sites More sharing options...
Lee21490 Posted February 16, 2014 Author Share Posted February 16, 2014 Figured it out. Lights were screwed up because the P/O Had setup trailer lights (By splicing into the rear lights) And just left bare wires under the truck. Water/mud caused them to short & backfeed through the multi-function switch. Cut it off & it works fine now. Link to comment Share on other sites More sharing options...
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