Overheating - OR NOT ??

[Csprod]

OVERHEATING ??

Hi,

I own a small raw water cooled diesel engine (BUKH DV8) and am (potentially) having a few overheating problems...

The main symptom I have is after running under load, the engine FEELS HOT and SMELLS HOT. Its too hot to touch, and has a smell thats hard to explain, but that i tend to associate with an overheating engine (entirely unscientific i know!).

Troubleshooting so far.....

1) Water flow at the exhaust (and anti-syphon tell tale) seems OK.

2) The temp alarm never sounds (its set at 80C/170F i think).

3) I wired up a temp gauge (from the same probe in the thermostat housing) and it cycles between about 50C/120F and 70C/160F

4) Checked the thermostat, it opens at 70C/160F

5) Checked the impeller - it was OK

6) Checked raw water inlet - no blockages

7) Checked the flow of the water through the pump - good throughput.


Am I dreaming or is it possible to have the engine overheating, but for it not to show on the water temp gauge (in the thermostat housing) ?

What to check next ??


Thanks,
Craig.

 

[penfold]

Unless the paint starts to peel off bits of it or the oil pressure alarm goes off it sounds fine; old engines 'breathe' a little when working hard, so you'll smell crankcase fumes and possibly oil and diesel if there's any small leaks. Laser contactless thermometers are cheap on ebay, if you're still concerned get one and point it at pertinent bits of the engine(exhaust elbow, sump, cylinder head) now and then; if nothing's climbing over 90C it's perfectly fine.

 

[VicS]

ITYWF that the thermostat should open at 60C

Puzzled that you can connect a temp gauge to the same sensor as the warning light. It's a dual sensor presumably ? Is it the correct gauge for the sensor?

Don't like the extent to which the temperature is apparently fluctuating. It may indicate some restriction to the water flow in part of the engine

There is a workshop manual at http://www.motoren.ath.cx/Download.php?filename=/bukh/Bukh_DV8LSME_Manual.pdf but its not very helpful.

Checking with a contactless thermometer is a good suggestion.

 

[Csprod]

Thanks for the info guys...

Vic - yes its a dual pin VDO temp sensor... Ive bench (kitchen!) tested it and it seems pretty accurate. My concern is that the place its measuring the temp from is not overheating, but the block etc is.

I was out again today, and the temp was sitting at spot on 60C when under load.

My gut feeling is a restriction in the water galleries or the exhaust elbow - but im just not sure what the next step is to confirm then rectify that. Its probably starting to get out of my range of ability, but at least ive done a big of leg work for the diesel mechanic that might save me a few bucks !

I might have a look at a contactless thermometer..... Ill report back the results !

Thanks again

 

[vyv_cox]

A rule of thumb with raw water cooled engines is that you should be able to rest your hand on the cylinder head for a few seconds. If not, it is overheating. I don't know the DV8 but on the assumption that its design is similar to that of the DV10 and DV20, have you checked the water injector into the block? On those two engines there is a small flange held by two Allen screws just behind the flywheel. It is possible to remove it without removing the flywheel first but you may need to cut down your Allen key to insert it. The injector is a perforated tube with a closed end. The perforations become salted up, causing exactly the symptoms that you have observed.