VP TMD40 overheating at high RPM

[Leighb]

The saga continues. We have sorted the calorifier problem and have piping hot water, however yesterday was our first opportunity to take her out to sea and open her up to see how the engines behaved.

All OK up to about 2500 RPM. Port engine - with calorifier - steady on 70C , Starb around 80C. On opening up further she accelerates eagerly to 3200 RPM which is fine, but the temp on the Starb engine also accelerated upwards.

Within a couple of minutes it reached 95C at which point I throttled back to 2500 and quite quickly the temp sank back to 80-85. The Port engine only rose to 80C.

Thinking about it I suppose the temp might have stabilised at the higher temp, but it seemed to rise so quickly that I was nervous and didn't want to push it further. Should I perhaps try again and see if the temp continues to rise, and if so, how high can I let it get?

The raw water impellers were replaced at the service last autumn, the intake strainers are clear, so no obvious cause there. Is it most likely to be the tube stack that needs cleaning out, or is there any other area that should be investigated? I assume, perhaps incorrectly that the thermostats would fail open so that the engine would tend to be too cool rather than overheat?

This engine incidentally has been fitted with the later TMD40B design heat exchanger which should be easier to clean?

Any comments/advice would gratefully received.

 

[volvopaul]

2 things to check

Rubber end cap distorted allowing sea water to pass by without making its route through the tubes .
Exhaust elbow partially blocked, check both stats are opening,
If it's s gearbox model check the gear coolers pipes are clean inside .
Clean the heat exchanger with rydelime.

 

[scottie]

Is there an air vent on the turbo water line? If so try venting at the banjo

 

[Leighb]

2 things to check

Rubber end cap distorted allowing sea water to pass by without making its route through the tubes .
Exhaust elbow partially blocked, check both stats are opening,
If it's s gearbox model check the gear coolers pipes are clean inside .
Clean the heat exchanger with rydelime.

Thanks Paul,
Is the distortion obvious on visual inspection? I have looked and felt round and it looks and feels perfectly even, do you need to dismantle to check it properly?
Re the stats, can they fail shut? If so that may be a cause?
Will get exhaust elbow checked.
I have read another thread about use of Redline, and it appears that can be done without much dismantling?
I do not know if it is a "gearbox model" or not. How to check? There are presumably cooling pipes going to the gearbox is this the indication.

Perhaps I should have said in my OP that it is on shafts with the MS3 gearbox?

It might be best to check the stats and treat with Rydlime and retest before undertaking any dismantling.

Scottie, thanks,
I can't see an air vent, the only visible pipes attached to the turbo look like oil pipes.

 

[scottie]

1 Out of production
Obsolete part, Early type, MO-13270
33 Out of production
MO 13485-13752
33 1 Out of production
Replaced by 1ea 846214 pipe, 2ea 846216 hollow bolt, 2ea 957174 packing, 2ea 957175 packing, 2ea 18344 clamp., MO-24591
33 Vent pipe 1 Out of production
MO 24592-, Obsolete part
34 Hollow screw 942806

Runs from thermostat housing to turbo small dia 6mm?

 

[dragoon]

It's invariably the oil cooler that blocks on my TAMD40s. It's under the heat exchanger - bit of a pig to get to. I usually drain the system, remove the heat exchanger, and remove the plate at the rear of the oil cooler so I can rod it through with a straightened coat hanger.

The banjo for the turbo is on the turbo - it's the bolt that holds the vent pipe that runs from the heatexchanger to the turbo. Just crack it open and check water dribbles from it.

The rubber boot problem is the "lip" on the inside that runs across the diameter of the boot. It goes soft, distorts and doesn't seal, allowing sea water to go from inlet to outlet of the exchanger without going through the tubes. From Keypart, these are about £95 each - at least they were about 2 years ago when I bought a pair.

I'll bet you have seawater that's calcified somewhere in the system (could be several places) - in the heat exchanger tubes, oil cooler tubes and possibly in the pipes from pump to oil cooler and heat exchanger to exhaust bend. Rydlyme is a good place to start - I flush mine out for a few hours now every season using a 12v circulating pump and a bucket to make a fluid circuit. It's a bit of pain as you have to break into the system before the exhaust, and on the inlet, but once you have set something up that works you can use it every year.

If you have MS3's you have the gearbox model.

 

[dragoon]

BTW, congrats on the Storebro. We have a Baltic 34.

 

[Leighb]

Many thanks all for helpful advice. Gives me more things to check.
Sounds like I need to take the cap off to examine it.

 

[No Regrets]

Don't waste any more time. Assuming the obvious bits are fine, reverse flush with Rydlyme the seawater system, and flush the internal system with the engine running and the thermostats removed. Watch the brown sludge come out....

It took me four years to cure my TAMD40b's of a higher speed overheat, now they are perfect, and run at no more than 85 degrees even when thrashed to bits. Previously they could overheat at the first whiff of throttle on the tideway.

Read my previous thread about TAMD40b overheat. I added Rydlyme (£120) into the exhaust elbow, through to the u bend before the impeller, which was a couple of allenmn keys, a couple of jubilee clips and an electric pump....

 

[Colin K]

Hi,
Just out of interest does anyone know what temperature they are supposed to run at flat out ? I had a blast for 20 mins at the weekend and they were stable at just under 90deg. I think that as they were not going above that then thats ok? Sure I read somewhere that an engine is most efficient at near 100 deg.

Cheers. Colin.

 

[Momac]

A friend with kamd 43's has cleared out his heat exchanger in an overheating engine (there were old bits of impeller in the tubes ). A new raw water impeller had been trashed in a few hours running. Then he found the raw water pump was worn. A water pump rebuild kit immediately improved the flow of water (a lot cheaper than a new raw water pump). A run in a few weeks time will prove whether it has worked.

 

[Leighb]

Fortunately, on the TMD40A/B the secondary seawater strainer is downstream of the seawater pump, so any stray bits of impeller end up in the strainer and NOT in the heat exchanger.

 

[Leighb]

Don't waste any more time. Assuming the obvious bits are fine, reverse flush with Rydlyme the seawater system, and flush the internal system with the engine running and the thermostats removed. Watch the brown sludge come out....

I am planning to get this done, I am not sure about your mentioning the internal system, do you mean the freshwater side, presumably you would have to drain all the coolant, refill with Rydlyme run it and then drain again and refill with coolant? Or have I entirely misunderstood.

 

[dragoon]

Hi,
Just out of interest does anyone know what temperature they are supposed to run at flat out ? I had a blast for 20 mins at the weekend and they were stable at just under 90deg. I think that as they were not going above that then thats ok? Sure I read somewhere that an engine is most efficient at near 100 deg.

Cheers. Colin.

I think they are supposed to run at just over 80C. When mine are running correct they site at 180-185F up to 3200 RPM - I never run them faster than that, but I've always seen as >185F as starting to overheat . At speeds sub that, they sit quite a bit lower
Picture attached....

 

[Leighb]

An update on an earlier thread.

We still have an overheat problem. Engine has been reverse flushed with Rydlyme, thermostats have been checked, gearbox has been removed and water passages checked, all clear, fresh water side has also been descaled. The engineer is now saying it could be something more serious such as a cracked cylinder head or a "split" ?? cylinder liner. I am not sure if these sorts of problem would only cause overheating at higher speed, as it runs happily for hours at around 2400RPM and 80deg.

A friend I was talking to yesterday asked if the compressions had been checked as poor compression on one or more cylinders could cause overheating when under load, is this something which should be done?

All suggestions gratefully received.

 

[volvopaul]

Did he check the exhaust elbow , I had similar job years back it was raw water flow pressure back up , de scaled elbow and cured problems.

 

[oldgit]

Assume that the overflow bottle is not mysteriously filling up after each run or that you have to constantly top up header tank ?

 

[Leighb]

No he didn’t! Although I have asked him to!!
However he said that he could blow through it at the injection bend. Would that rule out any constriction?
It seems to me that air at low pressure could easily pass through but a lot of water at higher pressure might not?

 

[volvopaul]

No he didn’t! Although I have asked him to!!
However he said that he could blow through it at the injection bend. Would that rule out any constriction?
It seems to me that air at low pressure could easily pass through but a lot of water at higher pressure might not?

Take it he’s not familiar with marine engines , take the elbow off and look up inside there are a series of holes where the sea water exits the elbow.
If possible carry out a sea trial with a pressure gauge between the sea water pump and the elbow . Measure the pressure should not be above 3 psi .

 

[Leighb]

Thanks Paul.
Next thing to do.