Heat Exchanger 4-108

[Randyonr3]

before I tear into it.. wondering if the "new style" perkins 4-108 heat exchanger is service-able or is it a throw it away and buy another?
reasoning... My temp is fine while running at about 1800 but as I increase the RPM, I see the the temp starting to climb.. at 3200 it climbs up to above 220.. going to change out the theromastate first and then approch the heat exchanger.....

[forsailbyowner]

think the temp readings are normal. Dont have the manual in front of me but believe 3200 is above the continuous duty rpm. Lowline exchangers can easily be rodded out or boiled clean. Discard when you start losing freshwater coolant out the exhaust.

[Dynamo1181]

Pull the tube set and soak in muratic acid dor an hour to remove scale. Check the impellor for missing blades. I have my max prop set for maximum rpm, 2800 at full throtle. I will overheat at that full throtle setting. I cruise at 80% of that with no issues. This is the "new" 4108 with a Bowman exchanger.
I might add that this setup and maintenance has worked well for 19 yrs and 6500 hrs.
A

[Jesse]

They are easy to service and very $pendy to replace.

[Unicorn Dreams]

After checking thermostat, check both water pump impellers.
I replaced my 4108 heat exchanger with one off of a 4236 I believe it was. Was told to get at least one engine size bigger heat exchanger for the added cooling capacity...

[blufootedboobie]

I was checking my 4108 today, with a hand-held lazer thermometer, and had similar temperature readings as Randyon3r. How long & hot is still considered "safe" or "normal" for these engines? I had heard that 180 is the normal operating temperature, and I get nervous running over 200 degrees, but am I being too cautious?

BTW my old, mounted analog thermometer readings were about 10-15% higher than simultaneous readings taken with my lazer. I trust the lazer more.

[btrayfors]

Yep. I did the same, over 15 years ago. The larger heat exchanger has made all the difference.

By the way, cleaning with muriatic acid and all the other treatments is no guarantee. At one stage before going to a larger heat exchanger, I did all the treatments, then compared the pressure with a new xchanger of the same size. The new one was much better, and worked on the engine for quite awhile.

Bill

[svHyLyte]

Originally Posted by Randyonr3

before I tear into it.. wondering if the "new style" perkins 4-108 heat exchanger is service-able or is it a throw it away and buy another?
reasoning... My temp is fine while running at about 1800 but as I increase the RPM, I see the the temp starting to climb.. at 3200 it climbs up to above 220.. going to change out the theromastate first and then approch the heat exchanger.....

Randy--

Post a snap of your heat exchanger. If it is what I think it is, like mine with rubber boots fore'n aft, pulling the boots and the tube bundle is a no brainer. Mine was pretty jambed up after who knows how long (potentially as long as 25 years). I soaked the bundle in a mixture of RydLime and fresh water over night, flushed it clean with fresh water (it looked like new), and reinstalled it with new boots and our engine runs like Topsey, never exceeding 180, even with the Gulf in the low 90's and us running at 3000 RPM or better. RydLyme isn't cheap, about $35 USD a gallon here, but it works very well and one really doesn't need all that much. And, it doesn't eat up the tubes as does acid.

FWIW...

PS: Replace the boots. They're cheap. Contact TA Diesel or Southeast Power if you can't find them in Taxifornia.

[lancelot9898]

I've used muriatic acid diluted in the past to clean the heat exchanger. I let it soak in the solution for only a few minutes, then soak it in a boric acid solution to neutralize, and then rod the tubes so that all are nice and shiny. It's been over 5 years since I've done the cleaning and the engine runs at 180 or 190 on the temp gage. A couple of days ago I replaced the salt water impeller and to my surprise a couple of vanes were broken. The water flow is much better now even though I had not noticed that much difference in flow prior to replacing and the engine temp was in the normal range. I need to remember to replace the rubber tubes on the exchanger some time soon.

[Minggat]

Had the same problem. High RPM, high temp. Spent a lot of money looking in the wrong places.....

Check your exhaust system for restrictions. Just a suggestion. One I ignored and paid dearly for it.

[blufootedboobie]

How hot is too hot?
Hearing your first-hand testimonials would be eye-opening.
Thanks. guys.

[btrayfors]

I'd say over 190 degrees. The expert mechanic who finally sorted out my Perkins some 10 years ago made me do a 5-mile trip up the Drake Channel in the BVI wide open. He said the engine should not overheat, even wide open. He was right, it didn't!

Bill

[Randyonr3]

Pulled the unit apart last night... wonder how the water even got through it.. sending it out today to be cleaned and preasure tested.. lucky me, I have a marine diesel shop right next door..
the reason I'm sending it out, I seem to be losing fluid and want to have it tested for leaks..........
by the way, that is a piece of an old impeller stuck in one of the tubes

[Blue Stocking]

Randy,

I think we should name that REEF after you.

[beneteau-500]

that tube stack looks like a serc ? tube stack you can still get them made in uk in birmingham if it is and you require one i can give you the contact details i put two new tube stacks in this yr for engine and g/box