Info needed - temperatures normal, excessive and too low

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If anyone has the info - I would really appreciate ....

I have a 4-107 Perkins engine and it has no temp. gauging. and raw -water cooled exiting into plain straight exhaust hose out transom.

So what would the temperature be expected mid engine block, exhaust pipe at possibly 1 or 2 ft from manifold,
(Based on engine having been run and at operating temp.) .......

Temp. too low

Normal expected temp.

Temp too high

Why ? I plan to fit digital temp probes at various locations at engine / exhaust ..... if anyone can suggest a location on the exterior of block to affix a probe .... I'm interested.
 
Amazing ... no replies ??

115 views .... but no posts ....

Surely there is someone out there with a reasonable idea of temps experienced on an engine ?

I will fit the probes and if no info forthcoming - will have to note the temps observed and accept them as norm.

???? No engineers out there with some info to help ?>>>>

/forums/images/graemlins/confused.gif
 
Re: Amazing?

The fitting point is seized and would take a large effort to sort. But for a small sum ... about a fiver for a digital temp item ... is cheaper anyway ... The exhaust doesn't have any provision for temp also ....

So instead of wrestling with the problem and probably failing .... plus the costs of the gauge etc. - why not digital's ??

Maybe I should have included that in original post ? Anyway - I would have thought that the temps themeselves may have been interesting to some ....

Seems I was wrong ... no prob.
 
Re: Amazing?

Not an expert but I have heard of a temp sensor that could be fitted by slackening a bolt and fitting it like a washer. It was a thermistor type ie it measures resistance which changes with temp. dont know where you would get one (possibly try ASAP supplies) .

You may notice the temp surging up and down as the thermostat opens and shuts .Apparently this is normal on a raw water cooled motor.So Im told.
 
OK...

OK, with raw water cooling you'd probably expect the engine to be between 60 and 70 degrees. If the exhaust got much hotter than 120 degrees you'd probably want to investigate.
 
Re: OK... thanks ...

That's better - don't you feel much better now ?

I understand the previous answer you gave ... but the second answer is more satisfying ?? to have helped ?????

/forums/images/graemlins/tongue.gif /forums/images/graemlins/tongue.gif /forums/images/graemlins/tongue.gif /forums/images/graemlins/cool.gif /forums/images/graemlins/cool.gif /forums/images/graemlins/cool.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

I'm surprised about the exhaust temp so much higher than the engine block ... but I do have a large amount of water cascade out of my exhaust ... previous owner had inserted a restrictor in the outer section at transom ... which was poor quality plastic ... finally went soft and closed of the exit - had to be ripped out. I haven't replaced the restrictor ....
 
Re: OK... thanks ...

[ QUOTE ]
I'm surprised about the exhaust temp so much higher than the engine block

[/ QUOTE ] Read it again - I said if it got much hotter than 120 you'd be wise to check why. Exhaust hose won't cope with much higher temperatures for long. Ideally, you should try to get the temp sensors inside the exhaust pipe.

And you're right, I feel much better now! /forums/images/graemlins/laugh.gif
 
Re: OK... thanks ...

No expert, but...

IIRC, if sea water goes much above 60 C, it deposits a kind of limescale - the stuff that blocks cooling galleries. As a result, I'd think that 55-60 would be about right in the block, probably a bit more inn the exhaust - perhaps 70 C, 'cos the speed of flow should keep the crud in suspension.

On Jissel, unless I'm really hammering to deglaze the bores or punch a tide, the water coming out of the exhaust is only just too hot to keep my hand in.
 
Re: OK... thanks ...

I've done the same thing on our engine. Unfortunately, it's a very different engine (12 hp single cylinder) so what I see on mine might not be right for yours. I bought a cheap thermometer kit from Maplins and an enclosure (I think it was about £10 some years ago). It displays degree centigrade or farenheit and has maximum and minimum alarms tht can be pre-selected. Obviously the minimum alarm isn't that useful and it isn't powerful enough to directly drive a big buzzer but you can also get kits that will do that! It is powered by one AA battery and that lasts at least 1 season. I change it every season but it might last longer!

The temperature probe is in the exhaust elbow. There is a brass plug conveniently in the top of it so I drilled that and Araldited the probe into it. For that reason, I don't know exactly what the gas temperature is as it goes through the elbow but the gauge reads about 48 - 50 degrees under all normal conditions. I did once have the thermostat stick and it went up to about 70 before opening with a jump. I believe raw water cooled engines need to run stone cold otherwise the salt water gets very aggressive and rusts them very quickly. Certainly, the water coming out of the exhaust always feels cool - barely warmer than the seawater!

If you engine runs fine now, maybe just try a different thermostat and check the temperature for each. If it's the same, just assume that wherever you take your reading, that's what it normally is!
 
um, well, this wn't workwillit? Cos the whole idea of heat exchanger is to maintain steadyengine temp of about 85 degrees. The inlet water could range in temp by 30 degrees, or alright nearer ten degrees.

Much more useful would be a vacuum gauge to shw when water not being pulled? instant indication of upcoming problem rather than temp, which lags.
 
Come again tcm ??????

Quote from my original question :>"I have a 4-107 Perkins engine and it has no temp. gauging. and raw -water cooled exiting into plain straight exhaust hose out transom."

My engine is RAW-WATER cooled without Heat Exchanger.

And I do believe it will work .... and anyway - what difference does it make - the engine will still overheat if a problem occurs and exhaust is still cooled by outflow water ... Heat exchanger or not ...

I did see a dual probe digital one time ... so will try and find that again ...

Given the cheapness of the digital probe and display ... I'm surprised that more are not used for stuff like this ...

I certainly do not want to risk causing damage replacing the old temp probe ... and some of the gauges I've seen only have blue / white and red sections .... no actual numbers ...

55 - 60 .... with possible 70 on exhaust .... that's what I'll plan for ... Many thanks.
 
Boiling point of seawater

is around 103 Centigrade varying with salinity so you have problems /forums/images/graemlins/blush.gif long before 120 Centigrade!
 
Re: Boiling point of seawater

I suggested that an exhaust temp above about 120 would be a cause for investigation. Interestingly, the Halyard Exhaust Alert system uses a 120 degree sensor, so my guesstimate maybe wasn't far out.
 
Hey Guys ... no problem ........

I know that my exhaust is actually not so hot that it gets near 100C ... probably more like 40 - 50 except right close to engine ... as I can touch the pipe - it passes close to one of my cockpit drain valves and hand has brushed it many times.

My idea was to be a simple fit and have the info as a guide in case of trouble. Even if I didn't receive info - which you guys have kindly passed - I would have noted the temp displayed on fitting and used that as reference. It's nice to know what it should ideally be though !!

I definitely think that my engine is running colder than that though ... but I do have a large amount of water exiting the exhaust when running.
 
Re: Hey Guys ... no problem ........

It IS supposed to run colder that that! That's the temperature at which the alarm is triggered so obviously Halyard expect normal temperatures to be lower. That said, I am surprised by how high it is. My exhaust is definitely barely warm to the touch even after several hours' sailing. I think my plastic silencer would soften at 120 degrees - possibly allowing the Jubilee clips to come off!
 
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