Coolant temp sensors~ temp gauge

[Leonator134]

Hi all, searched here and online, can't find exactly what I need.

My temp gauge is sometimes inop. Usually when the engine is cold, the needle works fine and makes its way up to the middle position no problem. But if the engine is hot and I shut it off and come back to the car and start it up the needle stays in the blue. However, after about 10 minutes of driving like this the needle will jump up to the middle again. I want to know where the sending sensor(s) are to check them/replace them. So, where are they? M60 V8 of course. Can't seem to find the info online.

Thanks!
Leo

[thatonedood]

Leo, I can give specifics when I get home from work tonight. Mean time I think there are 2 sensors on the coolant accumulator and one on the pass side of the intake mani. I'd go ahead and replace all three. I think one on the accumulator is what you need though

[Leonator134]

Thanks Paul, I really appreciated it! I don't know what the coolant accumulator is though Is it just the reservoir? M60 noob

[thatonedood]

People often call it something else. Coolant crossmember maybe? At any rate, it's at the end (firewall) of the engine. #1 below...

[Leonator134]

People often call it something else. Coolant crossmember maybe? At any rate, it's at the end (firewall) of the engine. #1 below...

Whoops! I edited my last post, I wrote "previous" when I mean "reservoir".. not sure how.

Thanks for the pic, will go take a look!

[K Fox]

Yeah, they got it already above. That pic shows both senders - one is for the DME and the other one is for the cluster gauge. That said, I now have a very similar problem as you describe - my temp gauge works intermittently. It's accurate when it's working, but it just comes and goes on it's own whims. I just replaced both of those senders on mine (I did the while valley pan job, and took the opportunity to replace those easily). So I doubt it's the senders - I'm thinking it probably one of the capacitors on the cluster going. They're known to go bad and cause all sorts of issues, and I've also had an issue with the message bar lights having not worked since I got the car (I tried replacing the bulbs within the first few days, no effect, so it has to be the capacitors on mine). Both are cheap fixes, really - the senders cost more at around $30, but pulling the cluster is required to fix the broken capacitors - you have to re-solder new ones in place of the old ones. The nice thing is that the parts only cost like $5 or so for the new caps - it's just a more involved project to get it fixed, though it's still likely only an afternoon either way.

Fox

[Leonator134]

Yeah, they got it already above. That pic shows both senders - one is for the DME and the other one is for the cluster gauge. That said, I now have a very similar problem as you describe - my temp gauge works intermittently. It's accurate when it's working, but it just comes and goes on it's own whims. I just replaced both of those senders on mine (I did the while valley pan job, and took the opportunity to replace those easily). So I doubt it's the senders - I'm thinking it probably one of the capacitors on the cluster going. They're known to go bad and cause all sorts of issues, and I've also had an issue with the message bar lights having not worked since I got the car (I tried replacing the bulbs within the first few days, no effect, so it has to be the capacitors on mine). Both are cheap fixes, really - the senders cost more at around $30, but pulling the cluster is required to fix the broken capacitors - you have to re-solder new ones in place of the old ones. The nice thing is that the parts only cost like $5 or so for the new caps - it's just a more involved project to get it fixed, though it's still likely only an afternoon either way.

Fox

Thanks for the info, Fox! I don't seem to valley-pan symptoms yet, so I'll wait on that one. However, the bottom of my PCV is oily... not burning any oil though (...yet). Will probably to do that soon.

Do we know which sensor/sender is for the DME and for the gauge? There's a white/tan one and black one... the black one has more pins..

[priler]

according to the bently manual under "Fuel Injection-DME" it's "rear of engine,in coolant crosspipe (white plug)".

...so i'm thinking the one for the DME is the one with a white plug.

[Leonator134]

Yes you are correct! I unplugged the black one and turned the key (based on an educated guess) and the gauge didn't register, so black is for gauge and white is for DME!

Thanks all!

[thatonedood]

Cool! Glad you got it figured out