Lehman heat exchangers/coolers

With about 10 years on them, I’m probably past due changing out the heat exchangers and coolers on our Lehmans—although much of that time has been in fresh or brackish water. Probably looking at ~$2K or better for all six components.

The three major sources seem to be American Diesel, Seakamp and Mr. Cool. I’d like to use quality cupronickel nickel parts. Does anyone know which are likely the best made and if there are others I should be considering?

Anyone?

I’ve always used SeaKamp. Mr. Cool buys and re-sells from others including SeaKamp. I don’t know who supplies American Diesel.

Edit: Not a Ford Lehman heat exchanger but from Mr. Cool’s web site.

I have replaced the heat exchangers on my Cats, the ZF gears and the 2 Onans with Sen-Dure Products heat exchangers. They were an exact match to the OEM units, are cupronickel and have removable end caps that to me is important. I even increased the size of the zinc anode ports to allow a larger anode.

Sen-Dure out of Ft. Lauderdale FL. which I could buy direct from, were easy to deal with and accommodated my changes without additional costs. Given the choice I would rather deal with the manufacturer of the item, rather than a retailer.

Their online catalogue is somewhat old school (or at least was) but was quite extensive. I don't know if they offer a product to fit your Lehmans.

Five years out, no problems to date. I don't expect that to change.

Thanks, folks. I talked to Brian at American Diesel. He recommends changing out the heat exchangers every 3,000 to 4,000 hours, which I’m nowhere near on the Seakamp heat exchangers currently installed. To be on the safe side, I’ll replace the plain copper engine and transmission oil coolers with cupronickel now since I don’t know how many hours the PO put on them. American Diesel’s components are made on Long Island. Seakamp’s are made in Seattle. I’m going with AD because Brian is extremely generous with technical advice and support, whether you’re buying from him or not.

Im with Angus on this.
AD (Brian) has been most helpful.
I am replacing all THREE Exchanges/coolers on my Lehman 120.

Brian is indeed wonderful. Great resource. I usually bought from him to help support AD. I didn’t want them going out of business.

I took my heat exchangers (Ford Lehman) and coolers off in March, wanted to replace them as well, since they were also 10 years old. I had them shipped to a specialist company and they cleaned them, inspected plus pressure tested them. According to them they are still good for quite a few number of hours on the engines.

Perhaps yours need to be changed, but you may want to test them first, it might save you quite a bit of money.

Mambo42 said:

I took my heat exchangers (Ford Lehman) and coolers off in March, wanted to replace them as well, since they were also 10 years old. I had them shipped to a specialist company and they cleaned them, inspected plus pressure tested them. According to them they are still good for quite a few number of hours on the engines.

Perhaps yours need to be changed, but you may want to test them first, it might save you quite a bit of money.

Click to expand...

Thanks. I look at these as periodic preventative maintenance. The tranny coolers, in particular, would be a very costly failure as they dump seawater directly into the Velvet Drive housing, requiring a ($$$) rebuild. There’s arguments on both sides about using engine hours to determine the time to change them out. Unless you are in fresh water or do a fresh water flush, they sit in salt water year round—whether the engine is running or not. I don’t know the magic number of years, but I’ll probably put them on a 5 to 6 year schedule.

Try FredWarner1, on Ebay and maybe elsewhere. Does a lot of Lehman stuff. From memory he was cheaper for Seakamp than Seakamp direct. Good with shipping too. Helpful, he once sent some parts ontime to the hotel we had booked in Seattle.

Seakamp is my favorite source for HE.

Oil and transmission coolers are less than $100 each so follow Brian's recommendations for replacement.

Mambo42 said:

I took my heat exchangers (Ford Lehman) and coolers off in March, wanted to replace them as well, since they were also 10 years old. I had them shipped to a specialist company and they cleaned them, inspected plus pressure tested them. According to them they are still good for quite a few number of hours on the engines.

Perhaps yours need to be changed, but you may want to test them first, it might save you quite a bit of money.

Click to expand...

The problem with pressure-testing is that the test is only good on the day it was was done. The HX could be on the edge of failure, pass the test, and then fail the next day. How could your service provider possibly know where on the spectrum you are? Good for quite awhile? How long is "quite awhile"?

Removing, shipping or taking them to a service provider, paying for all that, not for me especially because there is no way of knowing how much longer those old HXs are going to last. Buy new and sleep easy.

catalinajack said:

The problem with pressure-testing is that the test is only good on the day it was was done. The HX could be on the edge of failure, pass the test, and then fail the next day. How could your service provider possibly know where on the spectrum you are? Good for quite awhile? How long is "quite awhile"?

Removing, shipping or taking them to a service provider, paying for all that, not for me especially because there is no way of knowing how much longer those old HXs are going to last. Buy new and sleep easy.

Click to expand...

You are right, I won't know for sure, but since the pressure test is done at a pressure much higher than the working pressure of the oil coolers I know the oil cooler will be good for at least quite a while, but how long ?

Luckily bringing them to this shop is not too much of a hassle, I take them off myself, drive there with my car, have them cleaned and tested and put everything back again.

Of course I can go for new ones, but the question becomes then: 'how often do I change them ?'

I had a Mercruiser 5.7 in one of my other boats, the risers would last exactly 1 season in the salt water, 1200 USD each, that became a bit expensive.

So for now I trust the expertise of the company that tested them, I have to start somewhere.

I think there is a replacement years spec for engine and gearbox coolers in the Lehman Manual. Might have been 20yrs, seems long, someone still with a Manual at hand could check.

Flushing the raw water system with fresh water before periods of non use will prolong the life of heat exchangers.

syjos said:

Flushing the raw water system with fresh water before periods of non use will prolong the life of heat exchangers.

Click to expand...

That is indeed a good idea. Will have to make some modifications, but in itself I should be able to arrange it.

There was a discussion about fresh water flushing of engines recently.

Someone will hopefully find it and post a link or you can search TF.

Fresh water flushing:

https://www.sbmar.com/articles/the-benefits-of-fresh-water-flushing-your-marine-diesel-engine/

You can buy an adapter cap for Groco strainers. I use it every fall to fill raw water system with anti-freeze. Easy to use and works well.

Trac Ecological 1285-B FLUSHcap - 2.5" (Medium) an Amazon

Mambo42 said:

You are right, I won't know for sure, but since the pressure test is done at a pressure much higher than the working pressure of the oil coolers I know the oil cooler will be good for at least quite a while, but how long ?

Luckily bringing them to this shop is not too much of a hassle, I take them off myself, drive there with my car, have them cleaned and tested and put everything back again.

Of course I can go for new ones, but the question becomes then: 'how often do I change them ?'

I had a Mercruiser 5.7 in one of my other boats, the risers would last exactly 1 season in the salt water, 1200 USD each, that became a bit expensive.

So for now I trust the expertise of the company that tested them, I have to start somewhere.

Click to expand...

Good point on over-pressure testing.