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furgo
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Joined: September 06, 2016
Posts: 944
Location: Southern Germany
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 Posted: Fri Apr 28, 2017 12:59 am Post subject: Which paint for fuel injectors |
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As part of a fuel line replacement, I've got 4 injectors sitting on my bench. I've removed the surface rust from their bodies and I'm looking at repainting them.
I'm wondering which paint I should use given that they will see a fair amount of heat.
As far as I can see, POR-15 seems to be what most folks use for rust prevention. Looking more closely at its datasheet, these are two bits that caught my eye:
• Heat resistant up to 450ºF/232ºC.
• POR-15® Rust Preventive Coating is sensitive to UV light and must be topcoated when prolonged exposure to sunlight is possible. Topcoating is not required for areas not exposed to sunlight.
Given that the injectors won't see a temp up to 450F and are not exposed to sunlight, I'm thinking two coats of POR-15 semi gloss black without an additional top coat would work well for this application.
I've also seen that some people use a VHT topcoat for paint around the engine area, which needs to be cured at high temperature before its first use. I'd be a bit wary of baking the injectors though (unless they can cure in-place), so that's another reason why I'm thinking of sticking to primer coating only in this case.
It's my first foray into the world of automotive paint, so I thought I'd check with other folks with more experience in this area. Thanks!
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'79 Westy, P22 interior, FI 2.0 l Federal, GE engine (hydraulic lifters)
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raygreenwood
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Joined: November 24, 2008
Posts: 21512
Location: Oklahoma City
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| Posted: Fri Apr 28, 2017 11:23 am Post subject: Re: Which paint for fuel injectors |
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| furgo wrote: |
As part of a fuel line replacement, I've got 4 injectors sitting on my bench. I've removed the surface rust from their bodies and I'm looking at repainting them.
I'm wondering which paint I should use given that they will see a fair amount of heat.
As far as I can see, POR-15 seems to be what most folks use for rust prevention. Looking more closely at its datasheet, these are two bits that caught my eye:
• Heat resistant up to 450ºF/232ºC.
• POR-15® Rust Preventive Coating is sensitive to UV light and must be topcoated when prolonged exposure to sunlight is possible. Topcoating is not required for areas not exposed to sunlight.
Given that the injectors won't see a temp up to 450F and are not exposed to sunlight, I'm thinking two coats of POR-15 semi gloss black without an additional top coat would work well for this application.
I've also seen that some people use a VHT topcoat for paint around the engine area, which needs to be cured at high temperature before its first use. I'd be a bit wary of baking the injectors though (unless they can cure in-place), so that's another reason why I'm thinking of sticking to primer coating only in this case.
It's my first foray into the world of automotive paint, so I thought I'd check with other folks with more experience in this area. Thanks! |
They see very little heat at all. Another common myth propagated.....because people who tell you this do not think it through...or even measure it 
1. They have fuel running through them constantly that cools them...and what flows into them only stays there for a few seconds. The volume inside is low.
2. The injectors do not touch the head or the manifold.....unless you have seriously screwed up the injector seal installation...and in that case they will be leaking air massively .
3. The rubber injector seal fits so that the injector is dead centered...so that there is "0" contact between the injector body or tip and the intake manifold runner...which also runs relatively cool and has no actual contact with the cylinder head.
4. the injector is "suspended" in the round hasp by a rubber grommet so no contact with the intake manifold there either.
You get some radiant heat rising from the head...but on a bus its no issue.
On a car like my 412 with a fully sealed engine compartment....the injectors run about 125 F on the highway on long drives.
After shut down....in the summer..I have seen them rise to about 185 to peaks of maybe 200F...tops. They rapidly cool down once you start.
What you want is a relatively fuel proof paint. High heat is not so much of an issue.
The VHT paints are excellent. The barrel/cylinder paint should be excellent but I have not tried it on cylinders. Probably wont as I will probably plate mine with black nickel.
http://www.vhtpaint.com/motorsport/vht-barrel-spray-paint
This one I KNOW would work well. I have used it a lot. High heat and very chemical resistant. Follow the directions well.
http://www.vhtpaint.com/high-heat/vht-engine-enamel
This one will work fine
http://www.rustoleum.com/product-catalog/consumer-brands/auto/specialty-paints/engine-enamel
Ray |
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furgo
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Joined: September 06, 2016
Posts: 944
Location: Southern Germany
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| Posted: Fri Apr 28, 2017 6:03 pm Post subject: Re: Which paint for fuel injectors |
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| raygreenwood wrote: |
| They see very little heat at all. Another common myth propagated.....because people who tell you this do not think it through...or even measure it |
Good point. It was actually me not having thought this through rather than having read others' reports, so only myself to blame 
| raygreenwood wrote: |
| What you want is a relatively fuel proof paint. High heat is not so much of an issue. |
Thanks, that makes sense. I was thinking in terms of rust protection per se and temperature, so good thing I asked.
These all look good, thanks. The issue I see with VHT paint is that parts painted need to be baked in the oven to cure. As we only have the one oven in the kitchen, I can't really do the curing there. Also, without knowing the heat rating of the injectors, particularly the plastic part, I wouldn't feel too comfortable with the thought of perhaps damaging them by overheating.
After reading this I'm not sure if there is an alternative or whether I should just bring them to a shop to get them done.
Cheers.
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'79 Westy, P22 interior, FI 2.0 l Federal, GE engine (hydraulic lifters)
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raygreenwood
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Joined: November 24, 2008
Posts: 21512
Location: Oklahoma City
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| Posted: Mon May 01, 2017 8:43 am Post subject: Re: Which paint for fuel injectors |
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| furgo wrote: |
| raygreenwood wrote: |
| They see very little heat at all. Another common myth propagated.....because people who tell you this do not think it through...or even measure it |
Good point. It was actually me not having thought this through rather than having read others' reports, so only myself to blame
| raygreenwood wrote: |
| What you want is a relatively fuel proof paint. High heat is not so much of an issue. |
Thanks, that makes sense. I was thinking in terms of rust protection per se and temperature, so good thing I asked.
These all look good, thanks. The issue I see with VHT paint is that parts painted need to be baked in the oven to cure. As we only have the one oven in the kitchen, I can't really do the curing there. Also, without knowing the heat rating of the injectors, particularly the plastic part, I wouldn't feel too comfortable with the thought of perhaps damaging them by overheating.
After reading this I'm not sure if there is an alternative or whether I should just bring them to a shop to get them done.
Cheers. |
The plastic on the back of the injector is either nylon or polypropylene....cant remember.....but both are fine ro about 250-275° F .....constant......tops.
The VHT baking procedure is 200°. The injectors see 200°F off and on in the car after shutdown. It will not hurt the injectors.....just make sure your oven is accurate.
I would not bake the injectors in your kitchen oven....only because they have had gasoline in them. Otherwise....freshly cleaned and pianted parts give off very little smell or problem in the oven.
As the "how to use" data sheet states.....the injectors will bake themselves in the engine compartment over time. The gist os though that if you do not really have to bake them....dont get fuel on them and be careful installing them so you dont scratch them when installing because they are soft until fully cured.
This is how I baked my last set of painted injectors....and a few other small painted parts years ago before I bought a toaster oven for this.....I use a heat gun and a laser thermometer to heat them up on the work bench.
Take a small tin can.....like a tomato paste can. Clean it well. Remove the label
Attach a short piece of metal like a strap ....about 4"-6" long....to the end that is not cut out......with a screw or rivet.
You want a small diameter can whose walls sit close to the injector when you set it inside.
Use the steel strap you attached to the end of the can to clamp it to the edge of the work bench or a vise....so it stands out away from the bench or vise so you can work all around it.
I made four of these....one for each injector and riveted them onto a piece of metal.....so they sat in a four square pattern about 2" apart. This took all of 10 minutes.
Take the painted and dried injectors and set one into the center of each can with the pintle/tip end down....resting in 1/4" drive socket so they stand vertical and equal distance from the can sides.
Use a heat gun or propane torch with a diffuser.......and of you use a torch.....make sure you are away from all flammables....and cap the inlet sides of the injectors with plastic caps (I got mine at Ace Hardware). I have used both but heatgun works best.
Heat the cans evenly working around the outside. You will actually be heating the outer can surfaces to about 325° to 350°. You are turning the can surfaces into heating elements. They will radiate heat inward.
Once everything comes up to temperature......it works quite well. Really if you can spend 15-20 minutes doing this.....and then let them dry overnight to harden up.....kts enough baking to make them easier to install. They will bake the rest of the way over time.
My dad actually taught me this and it works well.
You can also do this by putting the cans in a pot of water and boiling....but the temp on the inside on the parts rarely gets over 180°. Ray |
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furgo
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Location: Southern Germany
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| Posted: Mon May 01, 2017 9:06 am Post subject: Re: Which paint for fuel injectors |
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This is excellent advice, thanks Ray!
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