TMD40b coolant leak

Leighb

Leighb

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Having at last resolved the overheating problem (hopefully) there is now a coolant leak. It seemed at first to be from the pressure cap. This was replaced as one washer was missing, but still a leak. After cleaning around thoroughly and dusting talcum powder around the cap the leak seems to be elsewhere. Where’s the next most likely place, I do have a flexible endoscope which may help but presumably I will have to look whilst engine is running?
Thanks for ideas.
 
I had a leak once between the turbo and manifold it only use to happen above 3000rpm used a flexible camera to detect.look for Brown/rusty water marks.it was a simple gasket change

Ash
 
Thanks that gives me somewhere to look. I have a feeling that it is at the front of the engine though as that is where the coolant appears in the bilge.
 
Mine had a mysterious leak from the Oil cooler inlet, where the seawater enters it's first port of call from the raw water pump.

The o ring seal is cheap as chips, and you can stick a few fingers in to see if it's partially blocked due to detritus inside (common on this engine!)

Worth a bash, as the build up of pressure in the oil cooler also reduces cooling.

My engine now runs as cool as a cucumber, and the bilges are a dry as a Nuns clunge :encouragement:
 
how much coolant are we talking about? drips or pints?
some engines don't like being full and blow some out of the header tank- there after the level doesn't materially change
common place for external coolant leaks are rubber hoses - getting old or corrosion where the rubber pipe fits on to metal parts
water pump seals getting old

easiest to spot when the engine is nice and hot and running as everything will be pressurised.
 
Drop some drain stain into the cooling system, you can get this in several colours and this will give a good visual indicator of where it is leaking.
 
Leighb said:
Thanks, but isn’t the oli cooler in the raw water circuit?
This is green coolant that is leaking.
Click to expand...

It may be pushing a bit out as it runs a bit too hot!?

Look at the state of the green plate the rad cap tightens onto, it may be corroded and not making a seal, you can clean it up to a point!
 
The saga with the starboard engine continues.
I think all the likely causes for overheating have been eliminated, heat exchanger checked and cleaned, injection elbow clear, the system has been rydlymed. New pressure cap fitted. It no longer gets so hot, Max 95C at 3000 rpm sustained. However it is still pushing green coolant out of the pressure cap, around 2 litres after 4-5 hours running. (I was incorrect in an earlier post.)
The possibility of a head gasket leak pressurising the coolant was suggested, but a test has been negative for the presence of exhaust products in the cooling system.
Something must be causing this, but what? Any further ideas? TIA
 
sounds like it is still running hot to me - have you checked the engine temps with an infra red thermometer ? What temp does user manual say I'm guessing @ 85 degs ish.
If you are 100% sure the sea water cooling is spot on, it might be worth pulling the fresh water pump off and the thermostats and having a look at the impeller and inside the water ways.
Maybe someone in the past didn't use anti freeze and its rusted up a bit ??????
 
When this happened on one of my TAMD60C it was a perforation in the plate heat exchanger. The seawater was at higher pressure so would push into the fresh system and out of the pressure cap. It started with very small quantities and gradually increased over quite a long period.

I finally found it by gently pressuring the removed cooler matrix through the sea water ports, using an air compressor and some demijohn corks, with the matrix immersed in a large sink. Despite trying to braze repair what was a tiny hole near the edge of one of the plates, nothing I tried would work.

I found best price for the cooler matrix at Keyparts ~£900. Volvo's price was ~£1,600. These might be getting scarce now. That was ~2013.

I did think about making new end fittings to accommodate a tube nest, e.g. from a Bowman cooler, but worked out the cooling surface area would be considerably reduced without a considerable extension at the square access cover end, and the mods to the VP castings would have been considerable.

This specific item would be the one thing that would stop me buying another boat with any Volvo Penta engine using this plate style heat exchanger.
 
superheat6k said:
When this happened on one of my TAMD60C it was a perforation in the plate heat exchanger. The seawater was at higher pressure so would push into the fresh system and out of the pressure cap. It started with very small quantities and gradually increased over quite a long period.

I finally found it by gently pressuring the removed cooler matrix through the sea water ports, using an air compressor and some demijohn corks, with the matrix immersed in a large sink. Despite trying to braze repair what was a tiny hole near the edge of one of the plates, nothing I tried would work.

I found best price for the cooler matrix at Keyparts ~£900. Volvo's price was ~£1,600. These might be getting scarce now. That was ~2013.

I did think about making new end fittings to accommodate a tube nest, e.g. from a Bowman cooler, but worked out the cooling surface area would be considerably reduced without a considerable extension at the square access cover end, and the mods to the VP castings would have been considerable.

This specific item would be the one thing that would stop me buying another boat with any Volvo Penta engine using this plate style heat exchanger.
Click to expand...


The TMD40b has a tubed heat exchanger, not the plate type on the TMD40a. AFAIK there is no sea water contamination of the coolant, which would be apparent if there was a direct leak between the two systems?
 
Leighb said:
The TMD40b has a tubed heat exchanger, not the plate type on the TMD40a. AFAIK there is no sea water contamination of the coolant, which would be apparent if there was a direct leak between the two systems?
Click to expand...
After it has discharged 2 litres do you then have to replenish a similar amount or is the engine water level still at its maximum fill level, or perhaps even fuller ? When this happened on mine there was no apparent contamination obvious, although I was not discharging nearly as much as 2 litres, just noticed a green trace appearing in the bilge.
 
superheat6k said:
After it has discharged 2 litres do you then have to replenish a similar amount or is the engine water level still at its maximum fill level, or perhaps even fuller ? When this happened on mine there was no apparent contamination obvious, although I was not discharging nearly as much as 2 litres, just noticed a green trace appearing in the bilge.
Click to expand...
Thanks. The 2 litres was the volume to bring the header tank up to the correct level, just covering the bar above the thermostats.
 
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