Genesis - Heat Exchangers - It must be Synchronicity!

[aslwhitby42]

Many thanks to the person who posted these steps. I used this process on my 80hp overheating Lehman engine to clean a 28 yr old H/E and it worked great. I am pretty sure the PO never had the H/E cleaned, many tubes were completely blocked and everything had a thick crust on it.

The only difference in my setup was that I had the H/E out of the boat already and used an old Rule 2000 GPH pump. The process only took about 30 minutes to complete with a larger pump. Liquid stopped bubbling and turned dark.

I can confirm that the solution will eat away zinc, which in my case was desired. The zinc anode had fouled the treads on my plug preventing it from being fully screwed in.

I have also seen previous posts about just dropping your Heat Exchanger by a radiator shop and for $20-50 they will clean it out for you.... This was not my experience. I tried this route first trying to save some time and got a repainted H/E with all the funky crusted tubes still hidden inside. I wouldn't go this route unless the radiator shop advertised they work on marine H/E and use an appropriate acid with pump to clean tubes, both sides preferably.

Scott

 

[SKYCHENEY]

This method also worked for me. I had one engine running up to a little over 190. Upon inspection, the H/E looked pretty clean, but the phosphoric acid flush did the trick. It now runs up to 182 and stays there at WOT loaded. It must not take much to get those temps to creep up on a 6v92 because it looked clean.

Thanks again for the tip, Karl. It sure saved alot of time.

 

[Genesis]

All high-output Detroits have insufficient cooling system capacity. Some are worse than others (the later year engines with DDECs addressed this to some degree) but in particular the higher-output (later) mechanicals were especially overstressed.

In cool (<70F) water this doesn't usually bite you, but in tropical conditions (>80F raw water) it will and does.

There are only two defenses that work, short of a complete re-engineering of the system, which is outrageously expensive:

1. Keep everything scrupulously clean. This means, for most people, annual service on these parts. Sorry. Its part and parcel of owning these engines.

2. If you're in a non-freezing area run distilled water with inhibitors. This gives you ~13% more heat-carrying and transfer capacity than a 50/50 mix of glycol, as water has a much higher specific heat.

The latter is specifically approved by Detroit for non-freezing climates; this is not a "Karl Hack".

Detroits are extremely intolerant of overheating. They will either crack cylinder heads or destroy seals leading to oil/water cross-contamination if abused and repairs are always expensive when this happens. Due to the use of a low-pressure system (7psi) there is far less margin than the higher-pressure, more modern 15psi systems.

The thing to remember about any engine is that once the thermostats are fully open any further increase in temperature means that cooling system capacity is exhausted, as you are then relying only on the delta for additional heat extraction. There IS some capacity to be had there, but not enough to be of material impact. With most Detroits running 170F thermostats any reading over 185F indicates the thermostats are fully open and you're out of room.

If you're running 180s then 195F is "full open".

5F beyond that is "never-exceed", so for most Detroits you should have overheat alarms set to ring between 190 and 195F.

 

[kwerges]

Will the phosphoric acid cause damage to the softer rubber in the engine, i.e. impellers, o-rings, etc?

 

[Genesis]

Uh, the phosphoric doesn't go in the fresh water side; it has not, in my experience, been a problem on the seawater side (on Detroits there is one large O-ring in the gland on the heat exchanger)

 

[GaryNW]

Just used the procedure on my 454's. Did the main HX's and then both oil coolers (engine and gear) by disconnecting hoses at the seacock and raw water pump intake. No impellers should be involved because you do not go thru the pump- it would block the flow. So I exposed the big round HX end gaskets and maybe 6' of raw water hose to the phospho solution. Remember that the procedure says to start-up the engines as soon as you have completed the flush! The exhaust will produce some foam for a bit. This short term exposure doesn't seem to bother the rubber.
Gary

 

[Genesis]

It won't.

Do recall that the solution comes in a plastic bottle!

 

[kwerges]

Will the phosphoric acid cause damage to the softer rubber in the engine, i.e. impellers, o-rings, etc?

Was hoping to use the same procedure in my old Cummins. Apparently more differences between the Detroit and Cummins cooling systems than I had hoped. Nevermind...

 

[SKYCHENEY]

Was hoping to use the same procedure in my old Cummins. Apparently more differences between the Detroit and Cummins cooling systems than I had hoped. Nevermind...

What is the major concern? The raw water side of any system should be able to handle this type of flush.

 

[hcalmar]

Found Klean-Strip® Phosphoric Prep & Etch at HD for @ $15. MSDS says it is 35-45% Phosphoric. Ospho's MSDS says it is 45%. BTW when I called they said they did not have it!
Hal

 

[REBrueckner]

When I cleaned my main engine heat exchangers following directions from this forum, I discovered rubber adaptors for different pipe sizes at Home Depot...I think they may be for drain systems in homes...

anyway, they have hose clamps on each end....black rubber or synthetic....so when I did my heat exchangers, I removed a raw water hose and slipped one of the rubber adaptors, 2" size end (I think, maybe it was 2-1/8") rubber end on a raw water pipe and the other on whatever clear vinly hose I was using.....about 1"....made connections easy, no drip.

 

[hcalmar]

Re: Genesis - Heat Exchangers -Did I screw up or were they due?

Just did the Genisis thing on my 671TIs. They have not been done since I had the whole thing taken apart and dipped in 2006. Ran backwards from the heat exchanger output with a 2" connection and a return from the first 7/8" zinc just north of the water pump with 5:1 water to Klean-Strip® Phosphoric. Ran 3 hours and it was still bubbleing though it had slowed down considerably.

Today at sea trial I had a couple of pin hole leaks that materialized, on the underside (through the paint) on the pipe that run from the water pump to the fuel and air cooler on both engines. No other leaks visible.

Where they just due to be replaced and I broke through all the corrosion holding them together? Did I screw up? Could I have caused damage inside the coolers/heat exchangers.

More to the point where do I find replacement parts? Can they be repaired? Is it just 2" copper pipe - cut out the bad /solder in new piece. They have a fitting for the stuffing box and 3/4" diversion for the fuel cooler.

Much appreciated.
Hal

 

[MikeP]

Sounds like the buildup in the system had plugged a hole/leak. Not really all that uncommon. I don't know the configuration of the pipe you are referring to on the 6-71 but unless it's a flanged fitting that bolts to the pump itself, seems like it could be easily fabricated or even replaced with hose. Or the bad portion alone could be cut out/replaced with hose.

If it's a flanged, cast iron (or whatever) fitting, then you could probably "repair" it with JB Weld after removing the pipe and cleaning it/applying the JB Weld to the inside of the pipe. It would certainly hold up for a season or two if you need to get the boat going and don't want to buy/find a replacement pipe right now.

I have seen "temporary" repairs done with JB Weld on cars/boats/equipment that ended up doing just fine for many years - to the point that "permanent" repairs were never done or necessary.

 

[Genesis]

Those pipes get perforated over time and the gunk clogs the holes - for a while, until you clean it out.

I'd be careful not dealing with this - if they're leaking they may be structurally for crap and if one splits wide open on you while underway the results could be quite unpleasant.

If the end with the flange (assuming there's a flange) is ok you can cut it off there, strip the paint and then use hose of the appropriate diameter at that point to replace the rotted section. Just be sure the part you're keeping is structurally sound.