Temp Gauge

I have a 1975 Aristocraft with 165hp inline 6. Temp gauge was not working last year so this spring I purchased new sender and new gauge. Also checked continence in wire from sender to gauge and it was fine. Still not getting any readings and I was out today for a long run. Engine getting warm but not overheating and running fine. When I touch wire momentarily to engine block I get a spike in meter when key is in on position. So whats my next move? Could it be a bad ground to meter?

Re: Temp Gauge

Bad ground between thermostat housing and engine block. Try touching the wire to the body of the sender... (You did buy a temperature sender and not a temperature switch didn't you)

Re: Temp Gauge

Yes a sender.

Re: Temp Gauge

lamphega said:

I have a 1975 Aristocraft with 165hp inline 6. Temp gauge was not working last year so this spring I purchased new sender and new gauge. Also checked continence in wire from sender to gauge and it was fine. Still not getting any readings and I was out today for a long run. Engine getting warm but not overheating and running fine. When I touch wire momentarily to engine block I get a spike in meter when key is in on position. So whats my next move? Could it be a bad ground to meter?

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A few questions.......
Did you remove the thermostat housing?
If you did, did you use the bottom gasket with the rivets when replaced (if not, you probably have a bad ground to the housing from the manifold)?
Did you use silicon sealer on the new gasket (this will prevent a good ground sometimes. Don't use silicon on that bottom gasket with the rivets)?

When you installed the sender into the housing, did you use teflon tape or silicon sealer to seal it (if you did, the teflon tape can / silicon insulate the sender from the housing)? Just use a small dab of regular gasket sealer or pipe dope (not silicon), if need be.

If you get the meter to peg when grounding the sense wire to the block, I would venture to say meter wiring is good. Betting on the sender not being grounded properly.

Re: Temp Gauge

Thanks, I have some things to check now next time on boat.

Re: Temp Gauge

OK, checked again today. Touching wire to sender to base makes the meter jump just like touching to engine block. So I think it is grounded ok, and wire to gauge obviously ok and gauge is brand new as is sender. How do I test sender itself although same symptoms with old sender and new one makes me think problem is elsewhere. Is it possible engine never gets to 125 as lake is only 59 degrees? Hard to figure as I took it on a good solid run last week. Next time I will take temp probe with me. It is a Faria 100 to 125 gauge.

Re: Temp Gauge

lamphega said:

OK, checked again today. Touching wire to sender to base makes the meter jump just like touching to engine block. So I think it is grounded ok, and wire to gauge obviously ok and gauge is brand new as is sender. How do I test sender itself although same symptoms with old sender and new one makes me think problem is elsewhere. Is it possible engine never gets to 125 as lake is only 59 degrees? Hard to figure as I took it on a good solid run last week. Next time I will take temp probe with me. It is a Faria 100 to 125 gauge.

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When you say "base", do you mean the base of the sender or the base of the housing? If you touch wire to "base of sender", then it's the sender that is either the wrong one or a bad one.

Bad Sender (if it is a sender and not a high temp alarm switch (common mistake with some)). It's an electrical component and they do come bad from the factory sometimes.

Everything you have done eliminates all other possibilities.

Re: Temp Gauge

lamphega said:

OK, checked again today. Touching wire to sender to base makes the meter jump just like touching to engine block. So I think it is grounded ok, and wire to gauge obviously ok and gauge is brand new as is sender. How do I test sender itself although same symptoms with old sender and new one makes me think problem is elsewhere. Is it possible engine never gets to 125 as lake is only 59 degrees? Hard to figure as I took it on a good solid run last week. Next time I will take temp probe with me. It is a Faria 100 to 125 gauge.

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Check the engine temp with an IR gun. It may be that there is no thermostat in the engine...

Re: Temp Gauge

I meant to the housing of the sender. And it has a new thermostat in it.

Re: Temp Gauge

Check the temp anyway. If the new stat is stuck open, it will never warm up.

Re: Temp Gauge

Will do.