Engine Compartment Painting

[Harry]

With the engine and tranny out and everything else out of the engine compartment, I am prepping all of the surfaces to prime and paint.  I plan to use a flat or satin finish under the hood.  It looks as though that was the original finish.

Also wondering whether to replace the forward wiring harness.  Are these available?  any idea on the cost?

Any additional advice?  Paint to use, etc?

[Benz Dr.]

Your paint under your hood has probably faded due to engine heat. I imagine that MB used the same paint all over the car.

Replacing a wiring harness is more work than you might want to get into.

[wwheeler]

The engine bay was the same paint and sheen as the body color. It looks more dull due to the severe environment it has been exposed to over the years as the Dr. says. But it was also subject to over spray from the body paint and the complications of spraying irregular surfaces in a tight area. All of which contribute to a dull look. I have painted several engine bays, and they are a pain to create a good uniform finish. They frankly didn't care as much about the finish in the engine bay on the assembly line.

[Charles 230SL]

Harry, I ordered what I needed to repair my 230SL harness from Rhode Island Wiring. They're 'pricey' but with exceptional quality - you won't be disappointed.

Their web-site: www.riwire.com. They have price listings for sections of the W113 harness - below is an excerpt for a 280SL:

1970-71 MERCEDES BENZ 280SL 113 Chassis
Note: All Connector Plugs and Connector Plug Terminals
Must be Reused from Original Harness
1a. Dash, Engine, and Headlight Harness [std.trans.] 1852.00 .-_-.
1b. Dash, Engine, and Headlight Harness[auto.trans.] 1852.00 .-_-.

Items 1a. and 1b.
015170 and subs.

2. Starter Harness 67.00 .-_-.
3. Transistorized Ignition Harness 89.00 .-_-.
4a. Emissions Control Harness [std.trans.] 446.00 .-_-.
4b. Emissions Control Harness [auto.trans.] 446.00 .-_-.
5. Emergency Flasher Adaptor Harness 125.00 .-_-.
6. Instrument Panel Harness 104.00 .-_-.
7. Body and Taillights Harness 477.00 .-_-.
Chassis# 015170 and subs.
8. Positive Battery Cable 57.00 .-_-.
9. Negative Battery Cable 18.00 .-_-.

[Harry]

Thanks for the feedback.  This car had been oversprayed with black satin which I hated and have removed.  I'm actually considering just using a rattle can for everything except the underside of the hood.  Seems like access would be much easier than trying to snake an HVLP gun into the various places, and probably do just as well a job since there are no large contiguous areas.

The wiring harness is completely free all the way to the firewall, draped over the top of the car.  So I would expect that replacing it now would just involve tying into the terminal box, although I'm sure that it's more than that.  Getting it free to the firewall alone was a job.  I'll have a look at the link for the wiring harness.  I just know that the original harness is "old" and looks it in placed.

Thanks very much!
Harry

[Harry]

WOW - $1707 for the front wiring harness and you have to reuse the connectors!  Looks like I'll probably be doing some reconditioning - but thanks for the lead!

Harry

[johnk]

Harry
A flat satin by nature is not as smooth as gloss or semigloss and is likely to be harder to keep clean.

Also if I may offer differeromg advice, having the engine and tranny out is a once in a car life opportunity to effectively do a nice job of an engine compartment refresh and I’m afraid you will have a long term disappointment but taking a short cut of using a rattle can at this point. I would say that a rattle can may be more difficult to control in engine compartment and is much easier to result in runs and an uneven finish specially if you are changing colors.

[Harry]

Thanks for the thoughts.  I understand what you’re saying.  Food for thought.

[wwheeler]

In regards to the rattle can. I agree that it will not turn out as well as a spray gun. But.... they have come a long way with rattle cans. You can get quality paint in a can from your local auto paint store. They can match your original color for about $20 /can. I would suspect an engine bay may require (4)? I have sprayed many things with spray cans with decent results. It is a bit of an art form.

First order is make sure the surface to be painted has some bite. 600 or 400 grit paper or even course Scotch bright will work. Clean with automotive degreaser. When you think you have it clean, do it one more time. Use a quality primer that the auto paint store recommends. When using the spray paint, lay a light tack coat on first and let it get tacky. Never start with a normal spray coat. Spray can paint loves to fish-eye. Once it creates Fish-eyes, the finish is wrecked. Continue with light coats until uniform. Don't worry about the finish being rough. The paint will flow if your timing is correct. At some point when the paint is uniform, you can start laying normal coats to build the thickness. Keep a look out for runs and fish eyes. If you get those, your coat is too heavy.

Also start with the hardest areas to reach and hidden areas. Finish with the most visible areas. I sprayed the front wheel wells on my W111 this way, and you would be hard pressed to tell the difference. The point here is that don't get in over your head and do what is comfortable for you skill level. You will be happier in the end. 
 

[hkollan]

Harry,

In addition I would use the opportunity to preserve the 7-8 ground connection points
in the engine compartment. They usually are ignored and just gets painted over.
Even most of the reputable restoration shops tend to "forget" this in my opinion
important detail.

Hans K

[Harry]

Thanks everyone!  I have been wiping down the entire area with lacquer thinner to remove any grease/oils, then sanding thoroughly with 220 grit paper.  I planned to prime next, sand lightly, then lay down the paint.  As with all paint jobs, the prep is where the work is.

[merrill]

years ago when i had the motor and trans out for rebuild i stripped, permatex rust treated and painted my engine bay with a single stage paint from Napa.

Napa mixed up the single stage in the correct color.

[wwheeler]

Lacquer thinner actually has trace amounts of oils in it. Your best bet is a wax and grease remover or sometimes called paint prep. You can get fish eyes with Lacquer thinner. In my opinion, 220 is a bit rough for paint surface prep. 400 is about the most course you would want. Otherwise you will see sanding scratches. If you use a primer with plans to sand afterward, make sure it is a "sand-able" primer. If it is not, the primer will just ball up on your paper. Even with the sand-able label, the spray can version is not super easy to sand. 

[BaronYoungman]

I would use a single stage for the engine compartment, more forgiving and easier to lay down, any good paint shop can mix your color. Just my 2 cents
Bob

[Harry]

Thank you all again.  All good advice and I will heed it closely.

[Joe]

With the engine out, you can sit inside the engine compartment and spray straightly, so coverage should be more uniform than if you leaned over a fender. I guess straightly's a word.
No one has mentioned a clear coat. Would that be desirable in the engine compartment, or on the underside of the hood?
Joe Melton
Colorado Springs

[Benz Dr.]

With the engine out, you can sit inside the engine compartment and spray straightly, so coverage should be more uniform than if you leaned over a fender. I guess straightly's a word.
No one has mentioned a clear coat. Would that be desirable in the engine compartment, or on the underside of the hood?
Joe Melton
Colorado Springs

I bet straightly is funner than crookedly.

[Pawel66]

With the engine out, you can sit inside the engine compartment and spray straightly, so coverage should be more uniform than if you leaned over a fender. I guess straightly's a word.
No one has mentioned a clear coat. Would that be desirable in the engine compartment, or on the underside of the hood?
Joe Melton
Colorado Springs

If you are using two component paint (base coat + clear finish) you have to use the clear coat as the base coat may wear off quickly and it looks matt in many cases. Underhood - if you are in the matt camp - use the matt clear coat. If you are in the gloss camp - use the gloss clear coat. I am in the matt camp and used the matt celar coat.

I think preparation of the metal sheet surfaces is the key. Wash, remove rust, apply protection, sand down a bit to matt, degrease, prime and paint. Mind which grommets and plugs are supposed to painted and which ones not (the plugs in inner fenders in late cars were painted). Consider replacing bad looking grommets - they will be bothering you later as they will look bad.

I am, actually, going through a similar exercise with my W463 300GE. Engine is in, I am dismantling all of the accessories fitted to engine bay sides. Horror...