Exhaust manifold fun!

[madhatter1]

So on 8-92 the dry section burns off paint and rusts. Today I did wire brush and cleaning of excess on inboard sides recently after seeing dust/crap after runs on the floor. Will do outboard sides when it's a little cooler out which is not far off. Question is how to treat the bare sections. If I do phosphoric acid should I then paint with grill paint or leave as is after treatment? Or skip that that and just paint? Painting will be done by expelling spray into a cup and brushing on. No overspray for me.

 

[racclarkson@gmail.com]

So on 8-92 the dry section burns off paint and rusts. Today I did wire brush and cleaning of excess on inboard sides recently after seeing dust/crap after runs on the floor. Will do outboard sides when it's a little cooler out which is not far off. Question is how to treat the bare sections. If I do phosphoric acid should I then paint with grill paint or leave as is after treatment? Or skip that that and just paint? Painting will be done by expelling spray into a cup and brushing on. No overspray for me.

I like Rust Bullet on those areas. It’ll brown, but it will also do its job.

 

[Briankinley2004]

I used the POR15 High Temp exhaust paint. It held up well for over a year and probably almost 200HR but it is starting to need another coat.

 

[madhatter1]

Robert, How long does the Rust Bullet last? We run on plane more often than not so our run hot that often. Product says 617 degrees max for 72 hours. Not sure what my EGT's are at 1800 RPM where we cruise.

 

[racclarkson@gmail.com]

Robert, How long does the Rust Bullet last? We run on plane more often than not so our run hot that often. Product says 617 degrees max for 72 hours. Not sure what my EGT's are at 1800 RPM where we cruise.

I recoated a few months ago. I’ve run it up to cruise for about three hours. The reason for the reacoat was I ran out of RB before I could do all four manifolds first time around (2 years ago). The 1/4 pint Whiteshell isn’t quite enough for twelve cylinder motors, and product doesn’t keep well once opened. The surface will turn darker shades of brown as you run on plane. I haven’t found anything yet that won’t discolor badly (maybe someone else does). And while I clearly exceed their temp rating planing, there’s not been a spec of corrosion where RB has been applied. As OP suggested, prep, including phosphoric acid, is essential.

 

[rustybucket]

Don't use Brake Caliper paint, it'll start flaking after the first good run.

 

[chuckbullett@gmail.com]

I recoated a few months ago. I’ve run it up to cruise for about three hours. The reason for the reacoat was I ran out of RB before I could do all four manifolds first time around (2 years ago). The 1/4 pint Whiteshell isn’t quite enough for twelve cylinder motors, and product doesn’t keep well once opened. The surface will turn darker shades of brown as you run on plane. I haven’t found anything yet that won’t discolor badly (maybe someone else does). And while I clearly exceed their temp rating planing, there’s not been a spec of corrosion where RB has been applied. As OP suggested, prep, including phosphoric acid, is essential.

Hi Captain Robert,

is the phosphoric acid treatment necessary for new metal as well? We’re painting the manifold pieces in the shop prior to bolting them in on our 8V’s. S
they should arrive next week.

thanks

Chuck

 

[racclarkson@gmail.com]

Hi Captain Robert,is the phosphoric acid treatment necessary for new metal as well? We’re painting the manifold pieces in the shop prior to bolting them in on our 8V’s. Sthey should arrive next week.thanksChuck

Not a paint expert, but phosphoric acid does etch most metals and etching, I believe, always helps the grip.

 

[madhatter1]

Wire brushed, wiped, and painted with rustoleum high heat black paint rated at 1200 degrees. A bit sore from contorting to slowly do an even neat job. Then cleaned engine room up. Only did the eye candy sides (inboard) so far. Looked at outboard side to see what I am up against and although they show rust they are not shedding like the inboard manifolds were.

Will wait on those since not a problem yet and see how the paint holds up. When it’s time to do outboard I need a materials, paint, cleanup plan and should probably pack a lunch. Want to do those in one trip, especially port side. Hav to work over the vacuum pumps

 

[DCMY #92]

The tail pieces on my 6V53s (circa 1963) deteriorated from the inside and outside (throwing off rust flakes and dust) on the two non-waterjacket sides. For years they were available at a reasonable price from DDC. The last one I replaced (4 years ago) cost $980. There were only 3 in DDC's inventory and they were in Germany.

Since I doubt I can find any of these several years from now, after I got the new one I sent all 4 to Jet Hot for ceramic coating. This is the coating used on many race car exhaust headers. Jet Hot used one coating on the inside (for salt water and diesel exhaust) and another on the outside (salt air environment). I don't recall the cost but it was not bad. The tailpieces are perfect so far.

I replaced my exhaust manifolds about 17 years ago at age 40 due to thinning at the exhaust end. I didn't send them to Jet Hot with the tail pieces since they are still likely to outlive me. If I disassemble them (take of the tail pieces and thermostat housings) and reverse them left bank to right bank at 20 years they should go 60 years. The uncooled sections of my 6V53 manifolds did not liberate rust flakes and dust like the tailpieces did.

 

[madhatter1]

Ran it over the holidays on plane. Paint has zero change in color. I think my EGT’s are well below the 1200 degree max on the paint spec. I’ll try to remember to report back in 6 months. Will definitely remember to report when it is time to recoat.