Lower engine cover refinishing

[Henrik]

I need to hear from those of you with fiberglass experience:

The thing is that the radiant heat from the exhaust manifold on my turbocharged VR6 has overheated the lower engine cover. I do have a heat shield solution coming so the time has come to restore/refinish the engine cover. You can see in the pics how the manifold has overheated it.

So what is the basic process? Will sanding (coarse => medium => fine) suffice? If so, what grit sizes should I go with? (Although I suspect I will need to grind down the bubbling...) Any gelcoat needed? My cover is/was painted with a fine hammer finish. Is that pretty typical? Any specific type of paint recommended? Is primer needed?

485774857848579

Thanks,

Henrik

[David T]

I need to hear from those of you with fiberglass experience:

The thing is that the radiant heat from the exhaust manifold on my turbocharged VR6 has overheated the lower engine cover. I do have a heat shield solution coming so the time has come to restore/refinish the engine cover. You can see in the pics how the manifold has overheated it.

So what is the basic process? Will sanding (coarse => medium => fine) suffice? If so, what grit sizes should I go with? (Although I suspect I will need to grind down the bubbling...) Any gelcoat needed? My cover is/was painted with a fine hammer finish. Is that pretty typical? Any specific type of paint recommended? Is primer needed?

485774857848579

Thanks,

Henrik

Start with 120# and if that isn't course enough try 80#. Then use 180# and finish with 220. Put a heat shield over the exhaust manifold and cover the bottom of the engine cover with a heavy metal foil. The original finish is hard to replicate. It was a flat black with some orange peel to it. You should not need a gel coat and a coat of primer will make the paint adhere better.

[DMC-81]

Hi Henrik,

I can't offer (Delorean) fiberglass experience, but I recommend SEM Trim Black (#39143) for the paint. That's what I used on mine, and I really liked how it turned out.

48655

I think if you have to take it the cover down to the bare fiberglass, then I would prime it first.

[Henrik]

Wow - that looks awesome, and thanks for the tip Dana. Also big thanks to David T for his input.

[Iznodmad]

Just curious as to what the underneath of the engine cover looks like if the top side has bubbled that bad? Better, worse, or about the same?

[Henrik]

Just curious as to what the underneath of the engine cover looks like if the top side has bubbled that bad? Better, worse, or about the same?

Good question. The underneath of the engine cover showed no signs of overheating; as it turns out it was the paint on the top side that had cooked and bubbled up. The fiber glass itself wasn't affected at all. Here is a pic of my 80 grit sanding efforts today:

48686

Onto finer paper, then primer!

[Henrik]

I noted that there was a thin strip of weatherstripping between the four engine cover grills and the lower engine cover; maybe that weatherstripping is just on my car (?) but it makes sense to ensure the grills are sitting firmly up against the engine cover.

So - assuming this weatherstripping is "official" - I do not see DMCH carrying it, and in my case I need high temp ditto, so I'm thinking either a bead of high-temp silicon sealant and allow it to cure before the grills go on, or to use high-temp weatherstripping from mcmaster.com.

Any other suggestions?

[Henrik]

Hi Henrik,

I can't offer (Delorean) fiberglass experience, but I recommend SEM Trim Black (#39143) for the paint. That's what I used on mine, and I really liked how it turned out.

48655

I think if you have to take it the cover down to the bare fiberglass, then I would prime it first.

Well... I sanded it down to the bare fiberglass, degreased it with acetone and primed it (bottle on the left):
49033
The result was somewhat blotchy but the primer is specifically for fiberglass so I didn't think too much of it:
49034
Then I sprayed the SEM Trim Black #39143, and........................ it looks like sh*t. Very blotchy:
49035
I added a few more coats after the pic was taken with no improvement.

Could it be the wrong primer? Could a coat of clear coat fix it? I haven't SEM sprayed the top side yet so I'm open for suggestions. I might just sand off the primer and try spraying the SEM Trim Black on the bare fiber glass.

[FABombjoy]

Are you painting under florescent light by any chance?

Looooong time ago, had some indoor garage space with florescent shop fixtures. I must have emptied 4 cans of Krylon onto my louvers but could not get them to lose the blotchyness. A friend with painting experience said, "lets carry this outside". Under natural light they looked nearly perfect.

I do feel like the primer patterns are showing through, tho.

[Henrik]

Are you painting under florescent light by any chance?

Looooong time ago, had some indoor garage space with florescent shop fixtures. I must have emptied 4 cans of Krylon onto my louvers but could not get them to lose the blotchyness. A friend with painting experience said, "lets carry this outside". Under natural light they looked nearly perfect.

I do feel like the primer patterns are showing through, tho.

No it was done outside. Interesting point though.

[Henrik]

An update:

I sanded everything down to the primer to the point where the primer was really thin but absolutely uniform in thickness, then degreased it (again) with acetone, then I recoated it with multiple, fairly thick layers of the SEM paint using l-o-n-g, continuous strokes from side to side. Here is the result:
49072
It's not 100% perfect but a ton better than yesterday and probably as good as it's gonna get, so I'm happy.

[airfireman1]

Just buy a turbo sock. that will stop the heat from damaging the lower cover. you can also get the Turbo casing ceramic coated together with the exhaust. Both options will reduces the engine bay heat.

[FABombjoy]

For sure, I have the DEI Ultra 47 on my T3 and it makes a big difference. Holding up very nicely so far.