VP TAMD60C gear oil cooler clean & pressure test

superheat6k

superheat6k

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Having hunted high and low for a leak on my stbd Twin Disc gearbox, I discovered a slow drip beneath the oil cooler above the box. This was running down and around the gearbox casing then into the bilge.

So pleased that I haven't got to remove the gearbox, I have now removed the cooler. The amount of solid crud inside on the seawater side was unbelievable, so much I suspect this was pushing the end cover away which clamps the O ring seal, allowing the seal to weep.

So, advice please ...

1 Operating oil pressure to the gearbox clutches has a max limit of 350 psi, and this is passed directly through the cooler. Once the new seals arrive I intend to re-assemble and squeeze with OFNitrogen to 360 PSI on the oil side, with an immersion test to look for bubbles.

Any reason NOT to squeeze with gas pressure rather than hydraulic pressure ?

2 If there is a leak around the periphery of the seal this will be immediately apparent.

3 if a leak appears from a tube or tube / end-plate joint any ideas how I can pinpoint it ?

The cooler requires the end caps in place as these position the O rings against the cooler insert & casing.
 
rafiki_ said:
This is one for VolvoPaul I think.
Click to expand...
Yes. I have been thinking of a coloured but thin fluid, like some ink, bit like a dye penetrant. I will only need to do this if bubbles appear from the water ports when immersed under pressure.

I did lose oil from my Port gearbox a few months ago, with no clear reason and no external leak, hence the need to verify if a leak to the waterside exists. I have now removed both coolers. The port cooler appeared much cleaner on the water side and has a slightly different tube nest, so I suspect this one has been replaced previously.

Volvopaul's direct experience here definitely appreciated, before I reinvent the wheel.

If its a single tube I should be able to fill the offending tube completely with epoxy putty, but despite its small size there are approx 100 individual tubes.

If its a tube / header plate joint then I think it would be new cooler time, although I would attempt to roll or swage it out.
 
are you sure the pressure is 350 psi - that sounds a lot to me. The oil cooler body is quite substantial but the end caps aren't that robust. If you think you have a leaking tube stack wouldn't it be more straight forward just to replace it or have it reconditioned? Also if the tube stack is leaking water into your gearbox, the oil would be emulsifying wouldn't it?
I think a good clean out and new seals would sort the leak. See what VP and others think.
 
The oil pressure of the g/box will overcome the water pressure any leak of oil will be evident on the cooler and our appear as an oil slick out of the exaust.
 
whoa! I really wouldnt test with any gas to 360psi even under water. There is an awful lot of stored energy. as the gas is compressable.

You really need to test hydraulically.... bit of kit called a bucket tester that pumps hydraulic fluid or oil into the cooler, as you watch the pressure gauge. Any leak will show as the gauge dropping. As the oil is (nominally) incompressable you dont get a rapid loss of energy if a leak is present.

Recommend that you take it to a hydraulic company for testing.
Believe me a car radiator failing an air under water test at 30psi causes a big bang.
 
The operating pressure through the cooler is definitely up to 350psi. We routinely test refrigeration systems to this sort of pressure with gas, but I take your point.

If there is a leak it is very small, as the fluid loss is over months, not hours, so any oiliness is lost with traces of un burnt diesel.

I am looking at filling the oil side with a dyed water, or other thin fluid, then applying gas pressure from the test hose on top of the water, this way the gas volume in the test hose would be minimal, so an explosive failure would not happen. If there is a leak the dyed water will appear on the open seawater side at each end if the cooler body, and hopefully leave a tracer mark.

I will follow up with the results shortly, because the new seals arrive tomorrow.

I can also state just how effective B&Q descaler powder is. It works very well in an open bucket, so I am sure it will be as effective on the rest of the semi assembled system.
 
fair enuf, as long as you're aware of keeping the compressed volume low.
You could also use a fluorescent additive to the oil that you test with , then look for leaks with a UV light.
We use one for locating gearbox/hydraulic leaks
 
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