Perkins M30 Heat Exchanger salt water intrusion into sealed side of system

[nsailscal334]

Trying to figure out why we are getting salt water appearing in our anti-freeze on our M30. We pulled and cleaned and tested the heat exchanger, the heat exchanger bundle and the exhaust elbow. Replaced all of the hoses and gaskets (thank you Trans Atlantic Diesel for still stocking these!) and flushed thoroughly with distilled water. Then refilled with fresh anti-freeze. After running the engine for only a few minutes the coolant reservoir starts to rapidly fill and the anti-freeze turns milky in color (we know it is salt water intrusion since we tested with fresh anti-freeze and salt water and the mix looks exactly like what is overflowing from the coolant reservoir).
It also appears that the anti-freeze is not circulating properly. I've attached a picture of the anti-freeze that we pulled from the cooling reservoir and also the antifreeze that came off the bottom of the engine through the coolant drain/petcock. You can see that the solution from the top reservoir is milky in color (seawater intrusion).
Any thoughts, suggestions, any experience with this engine and similar issues? Thanks very much!!

 

[jssailem]

Have you observed any antifreeze drips on the belt or the front of the engine?

Possible the seal on the circulation pump (driven off the crankshaft) may have failed. That is where you my get seawater and coolant together.

The other suspect would be a failure in the tubes of the Heat Exchanger.

 

[nsailscal334]

Thanks for the response! We had the tubes cleaned and tested, they are good. No drips and we also replaced the main engine water pump and all the seals. Real head scratcher at this point!

 

[jssailem]

You say the easy suspects are not the cause.

Moving up the scale to unpleasant "hoses" and "Aw shXt" are gaskets and cracks.

This will take some heavy exploration non of it much fun. I know you have examined the primary places, but I would take one more look at the heat exchanger or another idea might be the water heater if you have engine heated water. Perhaps it is fresh water not salt water.

If no joy then one suspects it is in the engine that this is happening. That would not be fun.

 

[nsailscal334]

I agree, not looking forward to removing the heat exchanger again. It does seem like the likely culprit however, that and a close look at all the seals and hoses we replaced.
Thanks again for the suggestions and I'll try to post what happens

 

[Johnb]

Other than in the heat exchanger where else does raw and fresh water come together? On my Yanmar that is nowhere.

 

[kloudie1]

As Johnb says, the heatex is normally the only place seawater and coolant are close. Could it be that the exhaust manifold has a pinhole that is allowing exhaust into the coolant and causing the coolant to get milky ?
if not then heatex seals/gaskets would be prime suspects if you are confident that no tubes are leaking.

 

[nsailscal334]

We finally tracked down the problem! The Perkins M30 coolant system has rubber end caps on both ends of the exchanger that clamp on both the exchange tube bundle and the exhaust outlet. If you don't have both of the hose clamps on each end cap extremely well seated and tightened down, and then once you bring the system up to operating temp tightened again, raw water can seep into the sealed side of the system. Thanks for all the suggestions and it DID turn out to essentially be the gaskets and seals.

 

[ddines]

Congrats on tracking down the problem, good detective work. I am writing to inform other who have the M30 to be on the alert for the problem I discovered. The heat exchanger is subject to significant corrosion with diesel and salt water mixing in the exit of the HE (where the elbow attaches). Mine had developed a hole between the exhaust side into the coolant area. It was so brittle those small holes expanded into a huge hole which was difficult to patch with epoxy. Ordinarily the pressure from the exhaust should push the saltwater from the elbow out and away but on shut down which could allow salt water back in also leaking from the coolant into the exhaust area could find its way into the cylinder and cause hydro lock.

New HE's are very expensive and hard to find ($1500-2000) and many are shipped from overseas. So I tried buying a used one for about half that price and they shipped me the wrong one. (There are 2 types: cast iron and aluminum and switching types is possible but would require new hoses, and modification to the mounting). Plus the used one had enough corrosion on it that it would probably not seal. Despite his assurances that it would fit and that it was in usable shape, when I returned it, I had to pay shipping and a huge restocking fee. So my advice is to inspect any used one carefully before or bite the bullet and buy a new one.

Hopefully no one else encounters this but put it on your list of things to check when encountering a difficult to find issues.

 

[jibes138]

Regarding mounting of a heat exchanger: while motors have the mounting integrated onto the motor, on many designs this is not necessary.. on Universal diesels the HX can be remotely mounted on an engine compartment bulkhead. On the M25 they recommend a 3 inch HX but the OEM is 2 inches. The mounting bracket that bolts to the motor is for 2 inches thus you can either bend the bracket, buy a new bracket or remotely mount the HX off the motor.