UPDATE!!!!! IR temp measurements vs. reality

harleyfool · Sep 27, 2009

A follow up of a previous post:

4.3 GL Volvo - overheating since impeller replacement and despite intensive search (see previous post) I have been unable to find reason.

I removed thermostat and found engine temp gauge maxed out at 140 degrees. At the suggestion of another board member I picked up a temperature measuring device. He suggested an IR thermometer.

So this afternoon I start up the boat with muffs on. I let the engine heat up to 140 as noted on the boat's temperature gauge (no thermostat installed). I then started checking temperature readings on the external engine surfaces.

Thermostat housing - 95'
Hose from thermostat to water pump - 85'
Top of manifold - 80'
Lower portion of manifold closest to engine - 125'
Engine block area under valve cover 135'
My tongue - 91'
Boiling water on stove - 200'

So I am more confused. Sometime prior to the impeller packing it in the boat's temperature gauge maxed at about 160'. Now after my experiment I wonder if the sender/temp. gauge are faulty and perhaps under reading by 40' - but I'm not brave enough to reinstall the thermostat and run the boat to 200-220 to prove a point.

Any thoughts??

harleyfool · Sep 28, 2009

Re: IR temp measurements vs. reality

Re: IR temp measurements vs. reality

No comments .... so perhaps a simple question.

Could the circulating water thru the thermostat housing really be 140' when the measured surface temperature of the thermostat housing is only 85' ?

Note: The boat ran for a bout five minutes at 140' before I shut it down.

Don S · Sep 28, 2009

Re: IR temp measurements vs. reality

Re: IR temp measurements vs. reality

Measure the temp at the base of the temperature sending unit, that is where you will find the same temp as the gun.

Apollo75 · Sep 28, 2009

Re: IR temp measurements vs. reality

Re: IR temp measurements vs. reality

harleyfool said:
No comments .... so perhaps a simple question.

Could the circulating water thru the thermostat housing really be 140' when the measured surface temperature of the thermostat housing is only 85' ?

Depends where the temp sending unit is located --- small block chevy in the head --- good place going to show any flow problems and be fairly accurate.

Cold water may be right next to the thermostat housing and distorting your readings. I did not see anything on your readings that were hot. However, this engine is not under load --- only way to check it.

harleyfool ---> you still got that thermostat gasket in your pocket ?

Just joking --- good luck --- I will consider all posibilities.

Added : 140 - 160 degrees is not hot ---- okay -- I'll say it --- put the thermostat back in and check it with the IR gun

Well, well, well ----> Ronald Ray Gun

OFM

Don S · Sep 28, 2009

Re: IR temp measurements vs. reality

Re: IR temp measurements vs. reality

Depends where the temp sending unit is located --- small block chevy in the head

Not on boats. And this is about marine engines, not autormotive.

Without a complete model number or SN, it's impossible to give any kind of "where it is" information.

Apollo75 · Sep 28, 2009

Re: IR temp measurements vs. reality

Re: IR temp measurements vs. reality

Don S said:
Not on boats. And this is about marine engines, not autormotive.

Without a complete model number or SN, it's impossible to give any kind of "where it is" information.

I don't know where the temperature sending unit is located at ---> that is why I said "Depends".

Depends where the temp sending unit is located --- small block chevy in the head --- good place going to show any flow problems and be fairly accurate.

The rest was just a description of coolant flow that is fairly accurate compared to his that may not be accurate depending on where his temp sending unit is located.

Marine mechanics should know where it might be.

OFM

bruceb58 · Sep 28, 2009

Re: IR temp measurements vs. reality

Re: IR temp measurements vs. reality

Apollo75 said:
I don't know where the temperature sending unit is located at ---> that is why I said "Depends".

So if you don't know where it is, the reason for you posting where it is is because.....

...I guess I don't get it!

Don S · Sep 28, 2009

Re: IR temp measurements vs. reality

Re: IR temp measurements vs. reality

Marine mechanics should know where it might be.

Not until he gives a model or serial number. The 4.3GL has been used since 94 in several different setups (all carbed). Some were in the intake, some in the lower section of the thermostat housing. Now if the engine was in front of me, I could find it in a few seconds.

harleyfool · Sep 28, 2009

Re: IR temp measurements vs. reality

Re: IR temp measurements vs. reality

Temp sender is screwed into the thermostat housing facing away from the block. This is where I tried to take the temperature measurement from.

Don S · Sep 28, 2009

Re: IR temp measurements vs. reality

Re: IR temp measurements vs. reality

Was that the sender or alarm switch?

WHAT is your full model number. Need all the letters after the GL.

Apollo75 · Sep 28, 2009

Re: IR temp measurements vs. reality

Re: IR temp measurements vs. reality

If Don S does not know exactly where the temperature sending unit is at ---> how am I supposed to know where it is at ---> I have never even seen that engine in a boat --- I am a car / diesel mechanic remember

We all read the OP's post he stated :

"So I am more confused. Sometime prior to the impeller packing it in the boat's temperature gauge maxed at about 160'. Now after my experiment I wonder if the sender/temp. gauge are faulty and perhaps under reading by 40' - but I'm not brave enough to reinstall the thermostat and run the boat to 200-220 to prove a point."

Added : The OP asked --> "Could the circulating water thru the thermostat housing really be 140' when the measured surface temperature of the thermostat housing is only 85' ?"

It may be in a place that shows accurate engine temp at all times --- I don not know --- I just gave him something to compare with.

Maybe the sender is bad or the gauge --- guessing again --- trying to help --- why do you find so much fault ?

OFM

harleyfool · Sep 29, 2009

Re: IR temp measurements vs. reality

Re: IR temp measurements vs. reality

MY 2000 - Volvo 4.3 GL - PEFS

Don S · Sep 29, 2009

Re: IR temp measurements vs. reality

Re: IR temp measurements vs. reality

harleyfool said:
MY 2000 - Volvo 4.3 GL - PEFS

The sender on the thermostat housing is for the alarm switch, not gauge sender. The sender is located in the intake manifold as shown below.
Item #10. IF you shoot your temp gun at the base of the sender, it should be very close to what your gauge is seeing.

harleyfool · Sep 29, 2009

Re: IR temp measurements vs. reality

Re: IR temp measurements vs. reality

oops !!

In the past I had someone at the local Volvo-Penta dealer tell me where the temp sender was supposed to be and I must have misunderstood. I do see where the sender actually is. Thanks Don.

During my engine disassembly to locate the potential cause of overheating I noted the circulating pump has been leaking thru the weep hole. A replacement pump is to arrive tomorrow and I'll reassemble the engine (with thermostat) take some readings from the corrrect location. Will post an update then.

a70eliminator · Sep 29, 2009

Re: IR temp measurements vs. reality

Re: IR temp measurements vs. reality

Apollo75 said:
If Don S does not know exactly where the temperature sending unit is at ---> how am I supposed to know where it is at ---> I have never even seen that engine in a boat --- I am a car / diesel mechanic remember

We all read the OP's post he stated :

"So I am more confused. Sometime prior to the impeller packing it in the boat's temperature gauge maxed at about 160'. Now after my experiment I wonder if the sender/temp. gauge are faulty and perhaps under reading by 40' - but I'm not brave enough to reinstall the thermostat and run the boat to 200-220 to prove a point."

Added : The OP asked --> "Could the circulating water thru the thermostat housing really be 140' when the measured surface temperature of the thermostat housing is only 85' ?"

It may be in a place that shows accurate engine temp at all times --- I don not know --- I just gave him something to compare with.

Maybe the sender is bad or the gauge --- guessing again --- trying to help --- why do you find so much fault ?

OFM

I thought your post read well, forget it and move on.

harleyfool · Oct 3, 2009

Re: IR temp measurements vs. reality

Re: IR temp measurements vs. reality

Installed the "new" circulation pump. Ordered from the local Volvo dealer. Looks like an aftermarket, not as well made, but I'm sure will do the job. Also installed a new temperature sender.

Ran the engine on muffs at 1500 RPM up to a gauge temperature of 210 degrees. I think the water return out the stern drive was more than before.

IR temperatures

Thermostat housing (TH)- 128'
Hoses (left and right) from TH to manifolds - 85'
Manifold (left and right) - 84'
Hose from TH to circulation pump - 130'
Engine block where temperature sender is screwed in - 142'
Water draining out of stern drive - 88'

Notwithstanding the failed impeller, I now think that I am not overheating. Unless someone has any other ideas I now believe that the Faria temperature gauge has packed it in. I am sending it back for replacement.

Thoughts??????

bruceb58 · Oct 3, 2009

Re: UPDATE!!!!! IR temp measurements vs. reality

Either that or the sender is bad. There should be a spec for the sender...basically a resistance number vs temperature. You would make this measurement with the wire disconnected.

a70eliminator · Oct 3, 2009

Re: UPDATE!!!!! IR temp measurements vs. reality

Yep sounds like a sender/guage mismatch, not unless your guage ia reading celsius, 212 farenhieght is somewhere around 100 celsius, not sure of the exact conversion off the top of my head.

harleyfool · Oct 3, 2009

Re: UPDATE!!!!! IR temp measurements vs. reality

I suspect the original sender and the replacement are both fine. What has be confused is that the gauge is misreading (I think). It definitely misread AFTER the impeller packed it in. To be honest I have no idea when it started misreading. In fact I thought faulty gauges stopped working all together rather than reading high. I am confused.

Unfortunately it will be weeks before Faria sends me a replacement. I will be winterizing the boat soon so I will not have part three of the story until Spring....

deadstick · Oct 3, 2009

Re: UPDATE!!!!! IR temp measurements vs. reality

my thoughts....

swing by your local auto parts store pick up a cheap screew in temp guage, to make sure your guage is wrong. less than $10, takes 5 minutes to install.
outside temp means nothing unless you know what the outside temp is normally.

just my opinion...for what its worth

UPDATE!!!!! IR temp measurements vs. reality

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