Engine repaint ???soda blasting? what to do?

[Todd Pearce]

looks like I have the opportunity to remove my 6v92s and wilst out I would like to repaint them,Any advice welcome, aslo I am thinking it could be wise to do the short blocks at the same time,they run just fine and it seems silly to do them but they are out and its so doable,so any thoughts on that? and a good parts supplier?
Regards Todd

[scot]

I have had good luck finding parts at Stewart & Stevenson, Houston. If you run into "that's an old part".. just ask for John in used parts. John and Robbie are both 30+ year Detroit gear heads and know your engines inside & out.

If you are painting the engines Detroit Diesel green, there is an official / OEM DD green sold by the gallon for around $80-100 bucks per / gal, S&S stocks it.

I would look more at the hours and ratings on the engines, not just that you have them out. If the 92s are set up above 1 hp per cu inch, low end (sleeves & pistons) rebuilds would be a good idea between 2000-3000 hours. Of course it depends on correct prop, bottom, etc. BTW, the term "92 series" means that each hole has 92 cu inches... so your engines have 552 cu inches.

If you have 450hp 6V92s the engines should, under normal conditions last 5000-10,000 hrs Between MOH and in many cases much more. If they are 575hp-600hp+ 6V92s.. don't look for much more than 2500 hours Between MOH. Good news is typically the only thing they need is pistons and liners...IF they have never over heated!

Of course ALL of these hour estimates are based on how the engines are treated!!

Good luck

[Todd Pearce]

Mine are 465hp Covingtons showing 1700hrs on the metres ,I bought the boat as a repo and therefore don't have any real history on the boat,they fire up fast and don't smoke,seem to pull full revs etc,but are unknown to me ,with very little in the way of documented history as the boat was stripped out except for all the original Bertram books and delivery documents which are complete(all 3 volumes, fantasic for a boat of this age),the boat arrived with spare filters for everything and with a little digging I found the boat used to belong to a coastguard guy/marine welder engineer, I found enough stuff on the boat, and a conversation with the marina owner ,to make me believe that the boat had been well cared for ,but I guess the attraction of knowing the short blocks are done mixed with the fact that they will be out,has me thinking
As for colour they are 1986 vintage and are white/rust ,the rusty bits drive me nuts,was thinking of soda blasting , then P10,then white of some kind , just not sure as I have not done it before thanks for your input
Regards Todd

[Bruce]

Covington was doing detroit conversions for Hatteras and having issues with various methods they used for extracting extra hp. About on par with J&T or junk and trouble as we knew them. GM was throwing fits until Penske bought detroit up and straightened out the issues. I think some time around your vintage.

Pop the inspection covers and check the cylinder walls. If you still see cross hatch patterns, leave alone. Also look for any piston scoring. But like Scott said liners and pistons are easy when out.

If you have a lot of rust soda blst is okay but make sure every port into the engine is well sealed off.

[Todd Pearce]

Thanks Bruce. Still looking for advice on the paint system,any thoughts
Todd

[Navatech]

Still looking for advice on the paint system

A few things to keep in mind:

1) Paint will not adhere to oil (and older DD's will have lots of that in the most inconvenient places)... Therefore I would start with a thorough degreasing of the engine...
2) If you paint over a layer of paint that has adhesion issues (flaking) your new layer will flake together with the sub layer... Make sure your substrate is sound...
3) A new layer of paint won't stop existing rust... It will cover it for a short time but then the rust will break through again... For both #2 and #3 soda blasting is the ultimate solution... It will even help with #1 (but you still should start with a thorough degreasing of the engine)...
4) Most paints are not suitable for painting an engine due to the temperatures involved (when running the engine)... You should shop for a paint that's specifically formulated for painting engines...
5) I personally don't like the original blue green metallic paint that DD used more often then not... Personally I prefer white, a very light gray or a very light cream (in descending order of preference)... The main reason being that they are relatively bright and will show leaks easily... Also, with brightly colored engines the engine room will look brighter... Possibly not an issue with smaller Bertrams but bigger ones, like my 46"6', definitely benefit (IMHO) from a brighter engine color...
6) Make sure (mask them with tape and paper) that you don't paint any of the rubber/silicone hoses!...

[CaptPatrick]

Make sure (mask them with tape and paper) that you don't paint any of the rubber/silicone hoses!...

Awhhhh, one of my tried, true, and ultra easy techniques:

Do every bit of masking, or as much as possible, with kitchen grade heavy aluminum foil. In most cases no tape is necessary, just scrunch it around hoses, wires, oil lines, etc.

Once done with the paint job, just rip the foil away. Takes less time to apply and removal is blinding fast. Far less expensive than masking paper and tape to boot...

[Todd Pearce]

Cap Pat,I Love it, you got all the tricky tricks up your sleeve, I love a good tip,and that's one I`d never have come up with in a thousand years, practical, simple, easy, gotta love it, so any other tips on the engine repaint,?

[MikeD@Lightningshack]

I have a fair amount of experience with engine painting. You can buy Bill Hirsch Engine Enamel in rattle bottles and standard brush paint cans. I have never seen anything hold the gloss on an engine better. It even holds well on water cooled exhaust manifolds.

Only problem is that they don't offer marine colors. If you can find something that matches I'd strongly recommend these paints.

http://www.hirschauto.com/prodinfo.asp?number=EE-QUART" onclick="window.open(this.href);return false;

Regards,
Mike

[Bruce]

I'd just paint fresh Detroits with a light coating of oil to get them started. (insert drum snap)

Sorry couldn't resist.

[Bob H.]

Todd if you soda blast you need to neutralize before paint or it wont stick...ask me how I know...had a Mack soda blasted and less than a year later the paint bubbled up, the soda attracts moisture..I used Capt Pats tin foil trick and It worked great..BH

[Bruce]

Thanks Bob for that info.

BTW isn't that how most of us learn anyways. At least I do.

[Todd Pearce]

Bob,thanks for the feed back, what do you use to treat them after the soda? ps I sent you a pm a little while back, love your work,I`am sure your as nuts as they come, just like the rest of us,you must be to achieve what you did on your 31,its a work of art,I was looking for some guidance on teak cappings for the cockpit in my boat,if you get the chance I wood love some help and insight on the job
Regards Todd

[Todd Pearce]

Hey Bruce ,does that oil come in gloss Detroit white??? if so I`ll take a drum or two,

[Mikey]

Hey, Bruce, I do it right cause I do it twice!

[Rawleigh]

Todd: Degrease with a hot water pressure washer and cleaner. I like Marine Clean from POR15, but the purple stuffs works good too. They are both alkaline based cleaners. Wire brush any loose rust or paint, spray with their Metal Prep to (kinda like Ospho, leaving a phosphate coating) and prime with POR15. Apply regular primer and top coat while the POR15 is tacky. I have had good luck with the POR 15.

http://www.por15.com/POR-15-_p_8.html" onclick="window.open(this.href);return false;

http://www.por15.com/MARINE-CLEAN_p_14.html" onclick="window.open(this.href);return false;

http://www.por15.com/PREP-READY-_p_15.html" onclick="window.open(this.href);return false;

[matt ciarpella]

Mikey, I used to do it twice when I was in my twenties. What is it your taking?

[TailhookTom]

Shouldn't Thudddd be commenting here? If anyone had experience with oilpainting, his motors certainly added a certain hue to not only the engine room, but they were quite capable of painting the transom as well as any other vessel within 100 yards.

Tom

[Rawleigh]

And I thought Detroit's never rusted because of the built in corrosion protection the leaky gaskets give! LOL!