oil temperature gauge or thermostat

Frederic

Cadet
Joined
May 24, 2011
Messages
9
Hi everyone, I have a 1999 Mercruiser 5.7L which overheated last year. My mechanic fixed quite a few things but I still don't get any oil temperature reading when the engine runs. He said he change the gauge (Ican see it is a different one), the sensor and even the wire but I get nothing Any idea what causes this? Incidently the trim gauge is also not providing any reading. Can this be related?
Thanks
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: oil temperature gauge or thermostat

You don't have an oil temperature gauge, just an engine coolant temp gauge. Probably the temp sender on the engine engine either on or near the thermostat housing. With the key in the run position, engine not running, Remove the wire from temp sender and touch a clean ground and see if the gauge pegs out. If it does the gauge is ok, and you probably have a bad sender.
Same with the trim sender. The sender fail quite often on the trim system, but the sender is on the gimbal ring, not the engine.
The two are probably not related.
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: oil temperature gauge or thermostat

I bet he used a standard automotive thermostat housing gasket... No brass continuity eyelets, no gauge reading....

Chris.......
 

Frederic

Cadet
Joined
May 24, 2011
Messages
9
Re: oil temperature gauge or thermostat

You don't have an oil temperature gauge, just an engine coolant temp gauge. Probably the temp sender on the engine engine either on or near the thermostat housing. With the key in the run position, engine not running, Remove the wire from temp sender and touch a clean ground and see if the gauge pegs out. If it does the gauge is ok, and you probably have a bad sender.
Same with the trim sender. The sender fail quite often on the trim system, but the sender is on the gimbal ring, not the engine.
The two are probably not related.

Thanks Don, I will have to wait for the weekend to check the sender.
As for the trim, I will look into it as well and I wonder if it is not corroded.
 

Frederic

Cadet
Joined
May 24, 2011
Messages
9
Re: oil temperature gauge or thermostat

I bet he used a standard automotive thermostat housing gasket... No brass continuity eyelets, no gauge reading....

Chris.......

Thanks, I have to wait for the weekend to check :)
 

Frederic

Cadet
Joined
May 24, 2011
Messages
9
Re: oil temperature gauge or thermostat

So I finally got to check the dauge and it works fine. The sender seems at fault. The part # I found is 12415 but it doesen't seem to be correct. My engime is a 5.7 L mercruiser Thunderbolt V on a 1999 Harriss-Kayot.
Thanks for your help.

EDit- looks like I looked into the wrong section because that is a mariner part, not a mercruiser. If anyone knows the excat part #, that would be great. Meanwhile I will keep looking. :)
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: oil temperature gauge or thermostat

-806490t
 

Frederic

Cadet
Joined
May 24, 2011
Messages
9
Re: oil temperature gauge or thermostat


Thanks achris.

I was looking at that and the sierra as well. Is Mallory better? Does it matter?

Edit - is there a post for the how-to change a sender?
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: oil temperature gauge or thermostat

1/ Remove the nut securing the wire to the sender.
2/ Unscrew the old sender.
3/ Screw in the new sender WITHOUT using thread tape.
4/ Put the wire on the end of the sender and secure with nut removed in step #1.

Chris......

OEM, Sierra, Mallory... Doesn't matter... Your money, your choice...
 

Frederic

Cadet
Joined
May 24, 2011
Messages
9
Re: oil temperature gauge or thermostat

1/ Remove the nut securing the wire to the sender.
2/ Unscrew the old sender.
3/ Screw in the new sender WITHOUT using thread tape.
4/ Put the wire on the end of the sender and secure with nut removed in step #1.

Chris......

OEM, Sierra, Mallory... Doesn't matter... Your money, your choice...

Thanks a lot Chris. I was worried I had to drain the fluid as well so that will be very easy. :)
Have a great day, mate!
 

Frederic

Cadet
Joined
May 24, 2011
Messages
9
Re: oil temperature gauge or thermostat

Well I got a new sender, check the gauge (it's working) but I still don't get any temperature reading. The wire looks fine as well and for arguments sake, I make sure there is water in the system. So I don't know what to do.

Anyone...???
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: oil temperature gauge or thermostat

Get an IR temp gun and make sure the engine is getting up to temp. Test right next to the sender.
 

Frederic

Cadet
Joined
May 24, 2011
Messages
9
Re: oil temperature gauge or thermostat

Get an IR temp gun and make sure the engine is getting up to temp. Test right next to the sender.

Okay, I got the gun and I will try this weekend. But what are the odds 3 senders, 2 of them brand new, being bad in a row? And the wire between the gauge and the sender is new as well.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: oil temperature gauge or thermostat

That's why I said get the gun, my guess is the engine is running cold which is why the gauge doesn't read anything.
 

Frederic

Cadet
Joined
May 24, 2011
Messages
9
Re: oil temperature gauge or thermostat

That's why I said get the gun, my guess is the engine is running cold which is why the gauge doesn't read anything.

Pardon my ignorance but is that a bad thing or a good thing?
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: oil temperature gauge or thermostat

If too cold, it's bad. Especially if someone took the thermostat clear out. The gauge sender would be seeing cold water, but the back of the engine could be overheating. That's why they have thermostats. To control the flow and the temp.
 
Top