95 Reinneil- Temp gauge jumping up and down

[bromann1]

I have a 95 reinneil with a alpha 1 mercruiser my temp gauge jumps around when on the water.any clues?

 

[Fun Times]

Does it jump around fast or slow...Such as key on key off type scenario or slow such as normal temperature to a low temperature then back up? Plus, 'any overheating/to high temperature readings/going to max temp?

Did this start before or after any service work performed?

 

[Bondo]

Ayuh,...... Welcome Aboard,...... Rebuild the raw water pump,.....

 

[04fxdwgi25]

Loose wire????

 

[bromann1]

Does it jump around fast or slow...Such as key on key off type scenario or slow such as normal temperature to a low temperature then back up? Plus, 'any overheating/to high temperature readings/going to max temp?

Did this start before or after any service work performed?

This started after service and changed impeller and it does move slowly up and down and some times just stays at 150°-170° it just bothering not know if infact I am overheating

 

[bromann1]

Ayuh,...... Welcome Aboard,...... Rebuild the raw water pump,.....

Thank you

 

[bromann1]

Loose wire????

Ok and the temp sensor is on the left side of the thermostat if I'm look straight at the engine from inside the boat? Sorry I know it sounds like a stupid question but I'm new to the boating seen lol

 

[Fun Times]

This started after service and changed impeller and it does move slowly up and down and some times just stays at 150°-170° it just bothering not know if infact I am overheating

If the engine was overheating then depending on engine model you have and accessories installed on the engine, generally you'd also be hearing a warning horn sound off once the engine gets too hot usually at which is typically about 196 degrees or more.

Being your temp swing is probably from normal temp and down to what? near 100 degrees I'll presume? it's better to be swinging low vs too high but still needs to be corrector as to low could start to foul out spark plugs and cause other engine problems to boot.

Being the cooling system was just serviced and the issue showed up thereafter, then it's time recheck the work performed before being able to move on to others.

Just a few things (of many possibilities) to start you out with, as mentioned, it's possible that you have a loose wire as the temperature sensor for the gauge was disturbed.
Could also be a bad grounding to the thermostat housing via a gasket that either doesn't have rivets in the gasket not allowing a good ground or the gasket was covered up with a non-conductive type of sealant or maybe the thermostat and or O-ring? /or cork? gasket was installed incorrectly.

What engine model do you have in your boat?
Engine serial number handy?

Ok and the temp sensor is on the left side of the thermostat if I'm look straight at the engine from inside the boat? Sorry I know it sounds like a stupid question but I'm new to the boating seen lol

Nope, definitely not stupid...It's very important to describe the way one is looking at the boat or engine as one's definition is often miscued to the seasoned boater or in this case the forum helpers.

Descriptions of what side for us is always considered Starboard (Right) or Port (Left) side of the boat when facing the bow (Front) of the boat from the Stern/Aft/Rear of the boat.

You being turned around facing the front of the engine, 'your now left is still the starboard side of the boat.

 

[04fxdwgi25]

Ok and the temp sensor is on the left side of the thermostat if I'm look straight at the engine from inside the boat? Sorry I know it sounds like a stupid question but I'm new to the boating seen lol

Should be 2 "sensors". Actually, one is a switch for the high temp alarm. Usually has a red body and normally on the stbd side of the stat housing and a tan/blue wire. The other one is the gauge "sensor" and normally on port side of housing and has a tan wire.

 

[dingbat]

Your boat is not a car a with closed, loop, pressurized cooling system.

Your boat is a raw water, open loop cooled. Temp fluctuations with varying engine loads is normal and expected

 

[bromann1]

If the engine was overheating then depending on engine model you have and accessories installed on the engine, generally you'd also be hearing a warning horn sound off once the engine gets too hot usually at which is typically about 196 degrees or more.

Being your temp swing is probably from normal temp and down to what? near 100 degrees I'll presume? it's better to be swinging low vs too high but still needs to be corrector as to low could start to foul out spark plugs and cause other engine problems to boot.

Being the cooling system was just serviced and the issue showed up thereafter, then it's time recheck the work performed before being able to move on to others.

Just a few things (of many possibilities) to start you out with, as mentioned, it's possible that you have a loose wire as the temperature sensor for the gauge was disturbed.
Could also be a bad grounding to the thermostat housing via a gasket that either doesn't have rivets in the gasket not allowing a good ground or the gasket was covered up with a non-conductive type of sealant or maybe the thermostat and or O-ring? /or cork? gasket was installed incorrectly.

What engine model do you have in your boat?
Engine serial number handy?


Nope, definitely not stupid...It's very important to describe the way one is looking at the boat or engine as one's definition is often miscued to the seasoned boater or in this case the forum helpers.

Descriptions of what side for us is always considered Starboard (Right) or Port (Left) side of the boat when facing the bow (Front) of the boat from the Stern/Aft/Rear of the boat.

You being turned around facing the front of the engine, 'your now left is still the starboard side of the boat.

Thank you for clearing that up for me I was so confused about the whole starboard/ port side thing ,lol I really didn't want to ask but thank you for educating me on that .

 

[bromann1]

Your boat is not a car a with closed, loop, pressurized cooling system.

Your boat is a raw water, open loop cooled. Temp fluctuations with varying engine loads is normal and expected

Didn't know that thank you

 

[bromann1]

Thank you for clearing that up for me I was so confused about the whole starboard/ port side thing ,lol I really didn't want to ask but thank you for educating me on that .

Let me get the serial # where would I locate it at?

 

[bromann1]

Let me get the serial # where would I locate it at?

Also I've never hear any sounds or alarms go off so maybe I'm just over thinking it I've been told never to let your boat over heat it's the worst!

 

[Fun Times]

Let me get the serial # where would I locate it at?

Sort of depends on what engine you may have...Inside the following link, click on the links that mentions 'Where to Find Mercruiser Stern Drive and Engine serial numbers'...,

Miscellaneous Mercruiser Information

How to ID an Alpha Style Outdrive, and History. Mercruiser Alpha ID and History.pdf - 4shared.com - document sharing - download - Don S Explainer documents. 'Pre-Alpha' drives Which 'Pre-Alpha' drive? Where to Find Mercruiser Stern Drive and Engine serial numbers. Drive units In-line Engines...

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