DD 6-71 Overheats

[Hattsaway]

One of my engine is running 200 F at cruise. I'm told this is bad. When I pulled the cover plate on the heat exchanger, it was covered in scale. Local DD service company quoted $2100, to pull, acid wash & shot peen the innards. I've read other posts which say it's ok to soak the cooling system in white vinegar or muratic acid and forgo the shot peen. I can think of better ways to spend $2100 and muratic acid scares me a bit.

Can I get by on the cheap by scaping off the accessible scale or by soaking in vinegar? I'll spend $2100 if I have to, but do I have to?

[Genesis]

Pull the core - its not that hard.

(Drain the cooling system first!)

Go to Home Depot and get a bottle of Phosphoric acid. Its green in color, and is used to get rid of rust and such.

Take 5 gallon paint bucket (empty!), put in Phosphoric acid. Immerse core until the bubbling stops.

Take second bucket, dissolve a couple of boxes of baking soda in water. Remove core from first bucket, insert in second to neutralize acid. Leave for a few minutes.

Reinstall core, refill cooling system.

You're done.

PS: Check the rest of the raw water system. Its a good bet that the rest looks as bad, and will need the same treatment (e.g. gear cooler, fuel cooler, etc)

$2100 to pull and clean the cores? My, how big a wallet you have, Mr. Boatowner. I can do both of my engines this way in a day.

200F is too hot. Don't ever let a Detroit go over 190-195 - you'll cook it.

[Hattsaway]

Yeah, I though $2100 was out of line too. That was the price quoted by Atlantic Detroit Diesel for removal, acid bath, & shot peening of cores, fuel & gear coolers on both engines.

I prefer phosphoric acid cleaning as opposed to muratic just from the safety perspective.

I've never pulled a core before and was wondering if I can get the job done leaving them in place. Perhaps by filling the raw water side with acid, let stand, and then run engines to flush?

Sounds like descaling should be part of regular scheduled maintenance. If so, how often should it be done? Would be a function of engine hours, calender time or just wait until cooling efficiency degrades?

[Genesis]

Yes, you can do it "in place."

HOWEVER, there is real value to tearing these down. You get to inspect them, which is valuable. Also, the bolts and end plates, seals, etc - all degrade. Don't take it apart regularly and some day you might not get it apart at all! Price out new H/Es (with cores - tank and all) and if you think $2100 is a lot of money.......

Also, the acid is not all that kind to seals. It probably won't cause trouble, but why take the chance, when you get value from doing it right anyway?

I do it out of the boat. Its cheap insurance and not hard to do. Just time consuming, at least the first time, until you figure out all the tricks on your engines (e.g. which order to take things apart in so you get the easiest removal, etc)

Go buy the gaskets (a few bucks an engine) and have at it. When you put the H/Es back together use RED Permatex on BOTH SIDES of the paper gaskets, and marine-grade grease (e.g. trailer bearing grease) on the bolts before you run them into the H/E tanks - this will keep them from seizing up on you down the road, and also keep the salt water from leaking on you.

On many Detroits there is a gland on the outlet side of the tank (essentially a big "O" ring) that seals the coolant and raw water sides from each other. Pay extremely close attention to that seal - both the O-ring and the sealing surfaces! If in doubt, replace the O-ring and if you don't like how the gland looks consider replacing it; if that seal fails you will likely lose coolant out the raw water outlet and not know about it until you overheat.

Don't neglect the gear coolers, and also consider replacing all the hose while you have it apart. I call transmission coolers "auxiliary sea strainers" for good reason - you'd be shocked at the amount of crap I've pulled out of mine.

I generally pull my coolers every couple of years or when I start seeing creep at cruise power. Its taken two years, and its also needed to be done in a bit more than one! While you're at it check the raw water pumps - particularly the wear plates and end plates to insure there is no scoring or damage, and the wear plate is not worn excessively.

Low raw rater flow for ANY reason will cause overheating as well.

Detroits have always been marginal on their cooling capacity. I live in Florida, and if I don't keep up on this stuff I have bad temperature creep problems and basically can't run beyond 1900 RPM or so on my 6V92s without overheating in the summer - but we get water temps in the mid 80s in the summer! If your water temps are lower you have a lot more margin to work with.

[Hattsaway]

Genesis,

If I clean in place, will all the dislodged scale collect at the exhaust shower head on a 6-71TI?

[jim rosenthal]

Karl, why would they advise him to have the cores shot peened? is this SOP, I've not heard of it. I will have this job to do on my Caterpillars this coming winter, they are long in years although not that long on hours. I did the aftercoolers, which are in the coolant jacket, last year, and they actually looked pretty good- the air circuit was gummed up but the fresh water side looked alright.

[Genesis]

Sounds like BS to me, or just a way to pump up the bill.

[rufuschamblee]

shot peening is used to increase surface hardness on metals and to stress relieve metal after machining or casting/forging processes. Shot peening would destroy a heat exchanger tube bundle. Maybe they meant bead or sand blasting. This is also bad for bundle. Acid, rods and a brush would be the safest approach for me.

Rufus

[Genesis]

... and have them boiled in their tank.

That'll take care of it.

Acid will handle the raw water side, but any silicate dropout on the fresh water side will laugh at acid baths.

The best option is the radiator shop - they'll get 'em spotless with their caustic bath.

Don't try that one at home - the radiator shops don't charge much to soak 'em good and its well worth it.

[Hattsaway]

Sorry for the confusion. I did not realize there was a difference. Either way, sounds like it's not needed.

Radiator shop wants $100-200 for a boil & clean. I think I'll take the advice of others and pull the core and have it done properly.

[Genesis]

Exactly what are they offering to clean for their $100-200?

[Irishlass]

I'd like to pull the fuel & gear cooler for a good cleaning this spring. Not sure how long it's been since last done.

Any tips & tricks I should be aware of? I think it will get messy when lines are removed. Same question for the oil cooler located at the bottom of the expansion tank.

[Nick]

Drain the raw water system. Disconnect the tranny hoses and cap the lines a nd the gear cooler fittings for the tranny hoses. I connected the hose from one fitting to the other on the cooler. Disconnect the raw water hoses on either end of the cooler. remove the bolts and take the cooler out. Dip it in a 50/50 solution of muriatic acid and water for a couple of minutes until the bubbling stops. You must use safety goggles and chemical resistant gloves. If you never worked with acids, take it to the radiator shop.

The fuel cooler is just as easy. Disconnect the fuel lines and the raw water hoses. Remove the fuel cooler. I replaced mine with a new one from Lenco in Amityville New York for about $150. The end caps on the old one looked deteriorated. You can get the formed 90 degree bend hoses for the raw water for the fuel cooler from your local Napa parts distributor.

As others have said they call the gear coolers strainers for a reason.

Good luck

[spartonboat1]

Just a quick note that Phosphoric Acid is sold in various strengths and under different names. Phosphoric acid, when applied to ferrous metals converts any rust/oxide in the form of a ferric oxide (some techie can correct me) into a Phosphate, due to other chemicals in the mix. Be sure you know what strength you are working with.

Phosphoric Acid is found in various dilutions in Naval Jelly, EndRust, "Metal Prep", various soft drinks, and in straight bottles. When the rust cures at the atomic level, it turns blackish. Navel jelly also contains Sulphuric Acid.

The phosphate in the acid converts ferric oxide (Fe2O3) into iron phosphate (FePO4) and water in a faster simple exchange reaction:

Fe2O3 + 2 H3PO4 ® 2 FePO4 + 3 H2O

The water is removed when the part is cleaned but the iron phosphate will adhere due to surface effects so that it does not wash away.

Thats more than I know...

There are Material Safety Data Sheets out on this stuff. Of course Muriatic acid was mentioned above.

[Walter Pereira]

A couple of years ago I had an overheating problem on my 43 MY with 6-71 TI's. OK at 1900 (180) would creep pretty fast at 2000 or more. I removed the HE cores and did the acid cleaning as specified in the DD service books and re-assembled the cooling system. I also replaced the impellers and cleaned the fresh water side as per the service manual. Results were fair as I was able to cruise at 2000-2100, but if I tried to go any faster they wanted to run up to 190-195. As a result when I got back up to NJ for the summer, I decided to dig deeper. My nephew in California skippers a large megayacht full time and they had some cooling problems due to scale buildup (including the air conditioning) He had his crew run a material called TRAC through a closed loop throughout the cooling system with a 110 V pump (impellers must be removed for this process) as recommended by the TRAC company and was very pleased with the result. The engines ran at normal temps at any RPM and when they did the HVAC compressors the heat exchange was vastly improved. I followed my nephews advice and bought some product from TRAC (in South Fla) and did my 6-71's. I was shocked at the crud that came out. A sea trial confirmed that I was able to pin the engines at 2400 and no sign of overheating. Naturally, I didn't hold that rpm very long but several minutes. I highly recommend this process as it de-scales the entire raw water system and does not harm seals or hoses. Disposal of the used product was also not a problem as it is environmentally friendly. If anyone is interested, I can probably locate the address and phone of the company. Respond on this forum or e-mail me at Walter@indoorcleanaire.com (cell phone 732-991-5665)

[mike]

www.tech-sales.com/dynami...caler.html (http://www.tech-sales.com/dynamic_eco_descaler.html)
Walt, the above site lists the dynamic descaler I believe you were referencing. Mike "Finally" 53'MY

[Walter Pereira]

Mike, thanks for your info on descaler - it's probably a similar product but I'm not sure. The product I was refering to is called TRAC Barnacle Buster. TRAC Ecological Marine Products at 1749 E. Hallandale Beach Blvd #185, Hallandale, Fl 23004 Phone 954-987-2722 Fax 954-458-3687 is the info on the label. I hope they are still around, it was really a great product.... solved my heating problems and really improved the air conditioning... Walt

[Traveler 45C]

Here's their site:
www.trac-online.com/tracb...buster.htm (http://www.trac-online.com/tracbarnaclebuster.htm)

G

[Genesis]

.... according to the MSDS, is either 5% or 20% (depending on if you have the "ready to use" or "concentrate") Phosphoric acid.

The rest is "non-hazardous" - meaning water or something like it, because even a surfactant of any strength needs a listing on a MSDS.

Seems to me that one could make up something essentially "as good" by going over the Home Depot, getting their "Ospho" (rust remover, primary ingredient Phosphoric acid), and then diluting it.

Assuming they would not package phosphoric acid as a "neat" substance (and indeed there is some kind of surfactant in the HD stuff - good, from my perspective, as it "wets" the surface better) I'd bet that its already a 20% solution or so - meaning that to make up an "equivalent" solution you could dilute anywhere from 1:1 to 4:1.

I have used this stuff (straight) as a "dip" for removed H/E cores, and it works VERY well.

[Traveler 45C]

Ok, this is getting real good. Question for Genesis: In your earlier post, you procedure called for neutralizing after the Phosphoric acid is used. The Trac product calls for flushing with water. Any thoughts?

G

[Genesis]

Flushing with water works too, it just takes more of it.

Note that they DO specify neutralizing the TRAC product before "releasing" it into the environment. Baking soda will do that for you, of course, since the MSDS just shows Phosphoric acid as its "hazardous" ingredient! Once you reach a pH over 2.0 its no longer considered hazardous and you can flush it overboard, although that ignores the nutrient content of the phosphorous, which could contribute to algae growth.

Indeed, I bet TRAC is nothing more than a very mild surfactant (e.g. glycerol, which wouldn't have a CAS entry) and phosphoric acid.

They also talk about the TRAC product "discoloring" some metals, which is characteristic of Phosphoric acid. It will "parkerize" iron and steel, for example, leaving a dark oxide layer on top of the surface (which, by the way, is a pretty decent rust preventative all on its own!)

The Ph-Ospho-Ric Plus is available at any Home Depot for about $13/gallon. Dilution somewhere between 1:2 and 1:4 should be good.

Be aware that this stuff is going to eat zincs, and plan accordingly (remove your anodes, unscrew the rods, and replace the plugs - re-insert or just replace the anodes when you're done.)

[skindr1999]

After you decide which path to take and all's back together fill the whole system with only distilled water (and whatever Nalcool is required). You'll get 10 yrs. or more out of your cooling system without repeat scale. Keep some in your engine room and only use distilled for topping off.

[Genesis]

.... and you won't get 10 years :b

More like one - or maybe a bit more - before a repeat is required. Especially down here in Florida.

[Traveler 45C]

Do you think this Trac product would do well flushing out the fresh water side?
G

[Genesis]

.... and I don't know how safe it would be for the engine's seals internally either.

On 92s, you have O-rings sealing the liners from the bore. Compromise those and you're rebuilding the motor.

There ARE de-scaling products for the fresh water side that the manufacturers will stand behind for this use.

I would select one of those.

[Traveler 45C]

Thanks again. I'll take your advice and give the HD product a try. My port 871 is running about 190 @ 2000RPM. I don't like that!
More questions for you: To neutralize, should I flush the raw water side with water & baking soda? Or just neutralize the diluted Phosphoric before I get rid of it?
G

[Genesis]

.... to flush with some baking soda in that water.

Just grab a second bucket, dissolve some baking soda in the water, and flush it through a few times.

This assumes you can't just reconnect the hoses and crank up the engine for some reason. If you can, it'll be flushed real good within a few minutes - those raw water pumps REALLY move the water.

[Walter Pereira]

Re: My experience with TRAC Barnacle Buster.... I followed the instructions to the letter and as previously stated the results were excellent. I am not a chemist, so I can't say that the Home Depot product is the same or not but I wouldn't doubt it. Generic products are quite common. Regarding the rinsing after use,,,, it's really very simple. Just reinstall a new impeller and re-connect your hoses then open the raw water seacock and fire it up -- easy rinse...

If anyone tries either process (HD or Trac or other) please post your results... P.S. I really appreciate this site for information.. Walt

[Genesis]

.... with most of these sorts of things is that you get the GEAR COOLER doing them.

See, on most of these boats, the gear cooler is on the SUCTION side of the pump.

Any kind of water pump is derated based on the amount of resistance to flow that the entire water path offers. A pump that can produce ~20psi of pressure, for example, is restricted by the outflow to a given extent.

However, since AT BEST that pump can pull 14.7psi of VACUUM, while 20psi of PRESSURE, the vacuum (suction) side is FAR more critical.

Restrictions on the SUCTION side are USUALLY where your problem is coming from - at least the biggest part of it. Taking out the primary H/Es and cleaning them does nothing for the suction side.

"Online" cleaning like this works as well as it does because it gets BOTH the suction and pressure sides of the system.

BTW, taking out the gear coolers is typically simpler than the primary H/Es. On my boat its four bolts for the cooler and the two raw water hoses and its out.

The fuel cooler is less critical - most of them are simply large-bore tubes with a counter-bore outside for the fuel to flow around. While the fuel won't get "as cool" if its fouled, it also doesn't restrict flow unless its GROSSLY screwed up.

[sussix]

this string was about to fall off page 20. Did not want to lose it yet. Hope the forum doesn't mind.;)

[jkp1]

I personally don't mind if someone revives an old topic from page 20. That's really one of this forum's shortcomings - inability to archive old threads. That said, I would hate to see the forum 5 years from now where half the board consists old posts people are trying to save. Until someone comes up with a better option, it's probably best if everyone check the forums last few pages periodically and print out topics of personal interest.

[John Dickson]

I am currently replacing my impellers on my Jabsco raw water pumps. Can someone tell me where the inside wear plate is so I can inspect? Also the inside of my end/cover plate has some wear scoring from the impellor. The engines have no overheating issues, I am only replacing impellers. Should the end plate be resurfaced or just replaced? Is the inside of the cover plate also the wear plate? Thanks

[BUSTER]

Moderate scoring on the cover is no big deal.If they are deep,I would consider resurfacing or replacing it.

[Traveler 45C]

This subject is covered in the FAQ section: http://www.samsmarine.com/forums/showthread.php?t=1483

Perhaps great old threads should be nominated for FAQ’s instead of reviving or letting them fall off.