How to test water temp when gauge is in question?

[cybor462]

Hi all I am getting ready to take this thing to the river tomorrow to see if I have any real problems with the engine (see other post) and I put the new thermostat in and ran it on muffs. The temp gauge shows 180-190 and then cycles back to 180 as the stat opens. I feel the sender or gauge is wrong so while running I held a plastic container under the exhaust (spent cooling water) and had a thermometer in it and it read a constant 120* I guess the water would loose a little temp after leaving the block I guess maybe 15* so that would give me 135* The stat is a 140 so I feel it may be the gauge or sender. Is this a logical way to test the water temp? If not how else could I do it?

Thanks
Jim

 

[Alumarine]

Re: How to test water temp when gauge is in question?

You could buy a mechanical guage and temporarily hook it up to the block. Some are quite inexpensive.

 

[cybor462]

Re: How to test water temp when gauge is in question?

Would you know where the heck the sender is? I looked and I can't see it. Well my eyesight is bad anymore and reading glasses are not too much better. I looked I see the oil pressure sender but not the water.

 

[Bondo]

Re: How to test water temp when gauge is in question?

Temp Senders are mounted In the T-Stat Housing.......

 

[cybor462]

Re: How to test water temp when gauge is in question?

Not on this one. Its a 1989 2.3 OMC Cobra (Ford) I just had the housing off to put the stat in and there is no sender there. I thinkiing its under the intake in that area or in the rear of the block.

 

[Bondo]

Re: How to test water temp when gauge is in question?

Ohh,.......... I Missed the part about it being an OMC/ Ford..........

 

[bruceb58]

Re: How to test water temp when gauge is in question?

Best to check the sender with an ohm meter. The guage manufacturer or the service manual will have a chart with temp vs resistance.

 

[cybor462]

Re: How to test water temp when gauge is in question?

Heah bruceb58 I only have the clymer which is not at all good. Its better than nothing.

 

[bruceb58]

Re: How to test water temp when gauge is in question?

Sometimes its worse though!

Heah bruceb58 I only have the clymer which is not at all good. Its better than nothing.

 

[cybor462]

Re: How to test water temp when gauge is in question?

Where would I get a better manual? I guess the same place I would need to get parts (nowhere)

 

[Boatin Bob]

Re: How to test water temp when gauge is in question?

Looks like the temp sender is sticking out of the block just above and back a bit from the oil filter....see item # 38 at this link 2.3 temp sender

 

[cobra 3.0]

Re: How to test water temp when gauge is in question?

$ 12.00 walmart temp guage with sending unit in the automobile section. Hook it up and see. It could be the guage too(on mine it was) and not the temp sending unit.

My Clymer for 1986 Cobra covers testing of the temp sending unit. (I must have that rare manual that works well.)

 

[cybor462]

Re: How to test water temp when gauge is in question?

boatinbob that is the oil pressure sender. Its the very large sender. I saw that one. Could not find the water temp sender. May be in the head itself. No matter anyway. Had it out in the river. All was well for the first 15 minutes. I was just putting around. Checked the engiine space and all looked good. So we got it up on plane and skipped along for 30 minutes and slowed to a crawl and the engine died. Started again and in neutral at idle died again. Looked into it and saw water dripping off the back side (transom side) of the carb. What I yelled?Pulled the flame arrestor and water was running into the carb and all over the base. It was coming from the vent hose from the oil cap. I got the engine started idled it up out of gear and pulled the oil cap and here we go water, plain water not mixed with oil but in its single state blowing out of the valve cover. So we have a cracked head. I marched my butt to the marina and told them we need to talk about this. He said Monday bring the boat and we will talk.
Finally know what my problem is. I will not pay for a head after I was promised the boat was 100% when I bought it. We never had it out without something falling apart. We have maybe, maybe 4 total run hours since we got it and all 4 of these hours were problem hours. We never had it out wothout trouble.

 

[Don S]

Re: How to test water temp when gauge is in question?

Item 38 in boatinbob's link IS the temp sender.

I guess now you are beginning to understand why OMC and OMC only, used the 2.3L Ford engine, and only for a few years.

 

[cybor462]

Re: How to test water temp when gauge is in question?

Don I am confused. If 38 is the temp sender then the sender in the head same place port side rear is the oil pressure sender? Seems odd they would put oil sender in the head and temp sender in the block normally the temp sender is always in the upper portion of the cooling path. Am I nutz or is this marine stuff weird?

 

[Boatin Bob]

Re: How to test water temp when gauge is in question?

This link shows the oil sender (much larger can type sender) item # 47
1989 2.3 oil sender

 

[Don S]

Re: How to test water temp when gauge is in question?

Am I nutz or is this marine stuff weird?

It's FORD, not "marine stuff" that is confusing you. The sender in the head is for oil pressure. Just unscrew it with the engine not running and see what comes out the hole!

What you need more than anything is a service manual and some test equipment. There is a lot more to a cooling system on a boat than on a car. Is your engine raw water cooled, or do you have a heat exchanger and a fresh water cooling system. When was the last time the impeller was replaced.

 

[cybor462]

Re: How to test water temp when gauge is in question?

Well thanks guys for all the help. I see the oil sender. I thought maybe OMC speced out the engine they wanted. The head is cracked. It is at the Marina now and the tune from the service manager has changed from I want to fix it for you as I do not do business this way. I brought it in today and now he is saying since I never told him I had any trouble they have to assume I wrecked the engine. Wow this was a shock as I told him each time I had the boat out that I had trouble either I called him or I drove the 30 miles and told him in person heck we only had it out 4 times for a total of less than 4 hours as each time ended with trouble, something going wrong. He said he wants to tear it apart and then I can talk to his boss. Sounds like I will get somewhere..) Sure I will.