Perkins D3.152 cooling problems

[buggsy]

Hi,

 

My engine over the Easter break has started to boil over, first after about six hours cruising and this time interval seams to be getting shorter. I have a keel tank and calorifier fitted and all last summer no problems.

 

I am going to start by changing the thermostat but any further advice would as usual be greatly appreciated.

I have bled the keel tank and if changing the thermostat doesn't help i suppose i will have to check the water pump.

 

The oil level seams ok so i don't think that it is the head gasket.

 

any further thoughts ?

 

cheers

 

Buggsy

[Alec Gatherer]

I think that the Perkins has a water bypass (to circulate water round the head-pump-head when thermostat closed)? If so, and my memory is much worse than it used to be (I think - I can't remember how good it used to be to be honest) then should the thermostat fail shut (as they usually do) the coolant will circulate round and round the head heating up all the time until it boils.

The quick, easy, and cheap way of testing the thermostat is to remove it then go for a run until it would have boiled. If everything is fine and dandy, it was probably the thermostat itself, which can and do fail occasionally. This can be double-checked by dunking it in a pan of water on a stove. As the water heats obviously the thermostat will open just before boiling point. If it remains shut that proves it to have failed.

I imagine you will need a thermostat to produce the domestic hot water (which you won't get whilst on the thermostatless test run) but at least you can test it out without paying anyone.

All this seems very Granny-sucking-eggsish, but at least I can delude myself that I am in a position to advise you (until the posts start arriving pointing out how flawed my reasoning is, and what a total arse I am).

[Guest]

As the symptoms have appeared quite suddenly (ok last season-not this)I agree it does sound like thestat has failed. It does seem logical to remove it as suggested and see what happens.

[John Orentas]

Hi Buggsy.

 

Your overheating or boiling could be caused by a number of things, however the most likely, easiest to isolate and lowest cost is the thermostat, it is therefore sensible to eliminate that before thinking about any others.

 

Fit a new one or simply remove the existing one and see how it goes.

[Cafnod]

Would concur with John, Alec and Stan, however have you checked belt tension? I would also check the weedhatch and make sure the prop is not restricted, likewise with engine off check the shaft rotates freely.

Finally if I may issue a caveat; should the problem be the stat do source and fit another as overcooling causes premature bore wear and is generally inefficient.

[Alec Gatherer]

Would concur with John, Alec and Stan, however have you checked belt tension? I would also check the weedhatch and make sure the prop is not restricted, likewise with engine off check the shaft rotates freely.

Finally if I may issue a caveat; should the problem be the stat do source and fit another as overcooling causes premature bore wear and is generally inefficient.

Wise words, and (not that I have experience, having an air-cooled Lister) essential if you use the engine coolant to provide hot water via a calorifier ( I would think).

[buggsy]

Hi,

i thought i would update you all on my problems. I purchased a new thermostat and radiator cap from C.A.S. a local automotive supplies. I relaced both and also checked the alternator/fan belt tension which suprisingly was a liitle slack due one loose bolt on the alternator and the alternator bracket appeared to be loose. Filled up with water and set off cruising.

 

Within 30 mins cruising the temperature gauge was showing 70 to 80 degrees, I checked the expansion tank but no signs of any expanding water. When i checked under the boards water under pressure was coming out of the header tank overflow pipe. Obviously the system is now pressurised. The previous cap had the rubber seal under the cap removed so i reverted to original cap and also the original thermostat had a 5mm hole in the body disc so i drilled a similar hole, this is perhaps a bypass? Now everything seams ok i hope.

 

Once again thanks to everyone for the helpful advice.

 

Cheers

 

Steve

[Ricardo]

... the original thermostat had a 5mm hole in the body disc so i drilled a similar hole, this is perhaps a bypass? Now everything seams ok i hope.

 

I think that wee hole is there to prevent an airlock forming when the engine water cools, otherwise the thermostat won't open if it's not touching the water.

 

Ric.

 

I found this interesting page when I was trying to work out why my thermostat had that funny little disc thing on the bottom: Bypass Thermostats

Edited May 2, 2006 by Ricardo

[buggsy]

Hi,

After changing the water pump, thermostat and carrying out tests to see if the head gasket had failed but getting a negative result, we have changed the head gasket and finally all is ok

 

So once again thanks for all the advice.

 

cheers,

 

Steve