engine temperature light on when engine cold
Thread Starter
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Senior User
Joined: May 2005
Posts: 129
Likes: 1
From: spokane WA
engine temperature light on when engine cold
Ok. Bought this 84 f250 4x4 6.9l truck. Been working on it fixing issues all weekend.
Drove it on the freeway yesterday, got off and as soon as I stopped the brake light and the engine temperature light went on. The guage showed normal temp(lower 1/4 of the guage).
Drove it home, let it cool down for about 3 hours, fired it up same thing. Drove it again then brake light went off but engine temp light is still on.
What should I check? any ideas?
Thanks
Oh yea, got the truck for $500 with 198,000 miles.
Drove it on the freeway yesterday, got off and as soon as I stopped the brake light and the engine temperature light went on. The guage showed normal temp(lower 1/4 of the guage).
Drove it home, let it cool down for about 3 hours, fired it up same thing. Drove it again then brake light went off but engine temp light is still on.
What should I check? any ideas?
Thanks
Oh yea, got the truck for $500 with 198,000 miles.
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 15
From: Nutter Fort, WV
How much pedal pressure did the brakes need to stop the truck?
The brake light turns on if the vacuum system is having problems.
Hard brake pedal and the heater defaulting to defrost are other symptoms of a failing vacuum pump or vacuum leaks.
Check the fluid level in the master cylinder and look for leaks in the brake lines on both ends if the fluid is low.
This is the sending unit location, front of the drivers side head.
Try unhooking the wire and reinstalling it.
Also inspect for shorts to the engine block.
The brake light turns on if the vacuum system is having problems.
Hard brake pedal and the heater defaulting to defrost are other symptoms of a failing vacuum pump or vacuum leaks.
Check the fluid level in the master cylinder and look for leaks in the brake lines on both ends if the fluid is low.
This is the sending unit location, front of the drivers side head.
Try unhooking the wire and reinstalling it.
Also inspect for shorts to the engine block.
Last edited by Dave Sponaugle; May 27, 2007 at 11:53 AM.
Thread Starter
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Senior User
Joined: May 2005
Posts: 129
Likes: 1
From: spokane WA
A little more info. Brakes were normal. When I bought the truck Friday the vacuum pump was bad. It has a new one now and is getting good vacuum still. I haven't checked the brake fluid since it happened, but friday it was fine(will check today). Brake light didn't come on when the vacuum pump was bad either.
There is a fair amount of wiring damage(idiots that shouldn't touch stuff) so I think that may be my problem. Need to go through and repair some wiring issues. Probably should just change out all the wiring.
New to diesels but a gear head so not afraid of jumping in.
I'd have to say I am really starting to like this diesel.
There is a fair amount of wiring damage(idiots that shouldn't touch stuff) so I think that may be my problem. Need to go through and repair some wiring issues. Probably should just change out all the wiring.
New to diesels but a gear head so not afraid of jumping in.
I'd have to say I am really starting to like this diesel.
Last edited by 72f2504x4390; May 27, 2007 at 01:16 PM.
Thread Starter
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Senior User
Joined: May 2005
Posts: 129
Likes: 1
From: spokane WA
Ok, if I disconnect the wire from the sender the light goes off so it has to be the sender. It is on even when dead cold in the morning. Well I was planning on putting some aftermarket guages on it, so I guess that is where I will plumb the temp guage. Problem solved, I think.
Brake light comes on and goes off. Not sure whats up yet with that. Maybe it has nothing to do with the temp light. Master cylinder is full, power assist seems to work right. Probably wiring.
Brake light comes on and goes off. Not sure whats up yet with that. Maybe it has nothing to do with the temp light. Master cylinder is full, power assist seems to work right. Probably wiring.
Thread Starter
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Senior User
Joined: May 2005
Posts: 129
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From: spokane WA
Front pads look nearly new. I think it does go on when I hit the brakes and then go off later just like you say.
I want to put on a new Master cyl. and flush the lines. It is nasty looking. I think I must have a warped rotor too as it surges while stopping.
Before I got the truck it pretty much sat only being driven 50 or 100 miles in the last couple years.
I want to put on a new Master cyl. and flush the lines. It is nasty looking. I think I must have a warped rotor too as it surges while stopping.
Before I got the truck it pretty much sat only being driven 50 or 100 miles in the last couple years.
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Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 15
From: Nutter Fort, WV
There is a balancing valve under the master cylinder mounted on the frame.
If you blow a brake line on either end it shuts that end of the braking system off and turns on the dash light.
Air in either end can cause the light to turn on as can a small leak in the brake system.
Another thing that turns that light on is the parking brake.
If the pedal is not tight against the stop when the parking brake is released, the parking brake switch could be what is turning the light on.
One of the parking brake cables sticking when released would cause the pedal to be loose enough to turn the light on.
If you blow a brake line on either end it shuts that end of the braking system off and turns on the dash light.
Air in either end can cause the light to turn on as can a small leak in the brake system.
Another thing that turns that light on is the parking brake.
If the pedal is not tight against the stop when the parking brake is released, the parking brake switch could be what is turning the light on.
One of the parking brake cables sticking when released would cause the pedal to be loose enough to turn the light on.
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Thread Starter
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Senior User
Joined: May 2005
Posts: 129
Likes: 1
From: spokane WA
I think its probably the balancing valve. Probably have a leak I haven't noticed. When I got the truck Friday, it had major fuel leakage and major tranny cooler line leakage so everything is oiled well. I pressure washed it, but haven't gotten all the oil off yet. Its hard to see where there are leaks and where there isn't.
Got all summer to get this thing reliable. Come snow time its got to be reliable(snowmachine hauler)
Got all summer to get this thing reliable. Come snow time its got to be reliable(snowmachine hauler)