Cosmetically, my 3.0L valve covers were fine -- there really wasn't anything to do there. Inside, they were black for oil. I probably didn't need to clean them, but I figured I might as well. The gaskets also needed to be removed and cleaned. I had also used a torch to remove the main pulley nut, which means I probably ruined the oil seal in the timing cover, so I had to replace that as well.
Valve Cover Gaskets
The valve cover gaskets were pretty solid. One of them came off pretty easily in large chunks, and just needed a little bit of scrapping to remove some residue here and there. The other one came off only in pieces, and required a lot of scraping.
In both cases I used my plastic scrapers to lift off as much of the gasket as I could. I scrapped of some of the remaining bit with razor blade, being careful not to gouge the metal, but one of the heads had a lot of hard to remove residue. I also tried to use my bristle disc, but it didn't really work as well as I'd hoped.
I decided to give Permatex Gasket Remover a try. I had three bottles; two of them were very fluid, while the other was thicker and easier to apply. You apply the remover to the remains of the gasket, wait about 15 minutes, and scrape it away.
This worked surprisingly well, turning the stiff bits off gasket into soft and easily scrapped of remnants. I was able to make short work of the remainder of the gasket.
Timing Cover Gasket
The timing cover gasket came off in much the same way, but since I knew what I was dealing with, I went straight for the razor blade now. I slipped the blade between the gasket an aluminum, wiggling it I pushed it along to separate the two from each other. This let me remove the gasket in large sections, and left little residue on the aluminum. What little was left I was able to scrape off directly with the blade or after applying gasket remover.
Timing Cover Oil Seal
Pressed into the back of the timing cover are two oil seals. The one I was most interested in replacing was the one for the crank, as I had to use a torch to remove the main pulley nut and likely damaged the seal.
I had never removed a pressed in seal before, but it wasn't very hard. The manual says you can get it out with a screwdriver if the cover is still on the engine, but it's pressed in pretty tightly, so I'm not sure how well that would work. If it's off the engine, the manual suggests just pressing it out with a socket.
I didn't have a press, but I did have a rubber mallet. I pressed my 35mm socket against the inside of the seal and whacked it pretty hard, pushing the seal towards the outside of the timing cover. A few strong hits and it popped out the front.
Installing the new seal (which came with my DeLorean Performance Industries 3.0L gasket set) was similar, but I skipped the socket and hammered it directly into the opening. If I didn't have a rubber mallet, I likely would have placed a piece of wood across the face of the seal to keep from damaging it. You also have to be sure to hit it square on so it seats properly. The new seal has a metal retaining spring around the inner rubber bit that helps it maintain its shape, but it can come loose if you're not careful, so don't lose it.
Distributor Oil Seal
The timing cover has a second oil seal where the distributor is mounted. I removed this one as well, flipping by socket over so that the smaller end could tap it out. I didn't bother to install the new one -- my conversion isn't going to have a distributor. Instead I'm going to make my own blanking plate to cover the hole.
Water Pump to Cylinder Head Piping
There are two small pipe adaptors that bolt to the front of the top of the cylinder heads. Hoses mount onto these and run to the water pump. Gaskets sit between them and the head, so i needed to clean them off as well.
Since the parts are so small, I mounted them in a vase and scraped off the gasket with a razor blade. Any remaining residue was removed with gasket remover.
Oil Residue Inside the Covers
The inner surfaces of all the covers were dyed in oil. While removing the gasket, some of the gasket remover had fallen in there, and when I wiped it away the oil was completely gone. I used a second bottle to soak the inside of the covers for about 15 minutes, then sopped it up with paper towels and shop rags. It did a remarkably good job of eating through the oil and revealing the aluminum.
When cleaning the residue from inside the timing cover, I was careful to avoid getting any on the oil seal, immediately removing any that got on there. This stuff eats through gaskets pretty well, so I didn't want to risk it damaging the rubber of the seal. I should have installed the new seal after cleaning the cover, but I didn't think of it.
I didn't get them perfectly clean (mostly because I ran out of gasket remover, and it's kind of expensive at $10 a can), but even this much wasn't really necessary.