Firing-up a car that's been sitting for a few years

[DanSel]

I bought a 1977 450SL a week ago. It's not running (according to the seller) and has been sitting for several years - he estimates 4-5 years.

This is his account of what happened:
Car was running fine when smoke started coming out of the passenger side cowl vent. He then _thinks_ the car died and he scrambled to pull the ground cable off the battery. Since then it's been sitting and he's not looked into fixing the problem. He thinks it's short in the wiring harness. I asked him if he's sure the engine died before he shut off the ignition and pulled the battery, but he can't say 100% that's the order since it was awhile ago and at the time it was his brother's car.

Regardless, earlier this week I removed the cowl vent and cover that goes over the heater blower/core under hood just to start poking around. Found some water sitting in the bottom of the area the heater core is in, but nothing obvious there and having removed the cowl vent, I now realize there was nothing to see there.

Yesterday I removed the glovebox liner, lower dash cover and side kick panel in the passenger footwell. I did notice a lot of loose, but tightly packed-in insulation that I believe was once attached to the inside of the lower dash panel and a few pieces of foam that had been added to keep everything tight up inside the dash I would guess. Behind the glovebox is a stereo amplifier and a control box for a car alarm. I inspected all the wiring and saw no outward signs of smoke, fire, insulation bubbling or brittleness, etc. that I'm used to seeing from electrical problems. While I was looking for the problem, I did notice on the top side of the amplifier (it's mounted vertically) some rust and the potential for water to have gotten in there. I also noticed that the power lead fell right out of the crimped connector attached to the amplifier so that easily could have been loose and sparking, doubt it would kill the engine however. The alarm system control box next to it looks fine, but would seem to be a candidate for killing the car if there was a short or fault in it, but as I said, it looks okay from the outside.

All the fuses in the fusebox look fine, none blown, all the heavy cabling going back to the battery and forward to the engine bay at that junction appear to be fine.

So my thought is with all the potentially flammable insulation removed, the wiring now being completely visible, and having found no real issues visually, I would like to try and start the car. I thought I'd push it out into the driveway, hook up the battery at the ready with an extinguisher. Hopefully it doesn't start smoking then and there. If it looks good, try to start the vehicle. I've not tried to start a car from cold that's been sitting this long however. I know what I probably _should_ do for the most part, but how much is necessary to just see if it will turn over?

My short list includes:

1) Battery. Is there a chance in hell of me being able to charge the battery and have it be good enough to fire up the car? I don't currently have a charger/tender that will handle a car battery, so I'd have to buy one (looks like a good Battery Tender is about $60, so not a big deal and I really should have one anyway). Or should I just go and buy a new battery and not bother?

2) Engine oil/filter. I assume I should change this before trying to even run the car for a short period or am I being paranoid? Should I try to get some oil down into the cylinders before I try to start it? The car has been covered for the years it's been sitting, it's only recently been uncovered exposed to rain and whatnot while the seller was trying to get rid of it, so there is surface rust and corrosion from exposure under the hood (valve covers, headers, air cleaner cover especially), but no deep penetrating rust that I've seen.

3) Fuel. I have no idea at this point how much fuel is in the tank without electrics, but I'm assuming I'll need to clean out the tank. I'm guessing I'll need to swap out fuel filter and probably fuel pump, but should I go further?

4) Spark plugs/wires. Seems like something I don't need to bother with unless I can't get it to fire, but maybe I'm wrong. My thought was to pull one of the plugs and see if it's corroded. If not, just leave them and the wires for the first start.

Later, if I get it running I'll bleed the brakes (at a minimum), do rear-end oil, grease fittings, trans fluid, radiator coolant, etc. Right now I'm just focusing on what I should do before trying to start the car in my driveway to see what's really at issue.

I do notice that there is a pretty good oil leak somewhere and I wonder if that's where the smoke came from, but the guy I bought it from seemed much more knowledgeable than that and he was positive that smoke was coming from the cowl vent which to me could only mean from under the dash where all that wiring and add-ons live.

Sorry for the long post, but I wanted to give good detail. I'm anxious to try and get it started since my Boxster is living outside while this car takes its garage space but I also don't want to do anything stupid to set me back in getting it running.

Thanks.

[mbbuff]

l. Buy a new battery.
2. Yes to the oil/filter change and down the spark plug holes. While you're at it run a compression check and put new plugs in. Cranking it with oil in the cylinders during the compression check should be enough to lubricate the cylinder walls.
3. IMPORTANT! Do not even crank it until the entire fuel system has been thoroughly cleaned, flushed and all filters changed. Check the fuel pump, which may be seized up from sitting.
4. As I said above, change the plugs, they're cheap. If you have an ohm meter, check the resistance of the ignition wires. If this is like a lot of the early Benz's the wires are solid copper with resistor ends at the plugs. Otherwise, they're probably resistance wires. Resistance wires, as a rule of thumb, should have no more than approximately 10,000 ohms per foot. Also, don't know if the SL is electronic breakerless ignition or has points. In any case it won't hurt to pull the cap and check its condition, as well as the rotor and points, if installed. If it has points, make sure the gap is correct. Generally, a gap of about .016 or so should get you in the ball park.

Let us know how it goes.

[DanSel]

Well, I found the cause of the smoke the previous owner told me about. The heater blower motor is burned out. The cover over it has about a quarter size scorch mark and the center of the blower housing is scorched and has some melting. The cover itself has a broken corner and a shot gasket so I'll be replacing that too so my replacement motor doesn't see the same fate. Thanks for all the good info so far.

[daw_two]

Originally Posted by DanSel

Well, I found the cause of the smoke the previous owner told me about. The heater blower motor is burned out. The cover over it has about a quarter size scorch mark and the center of the blower housing is scorched and has some melting. The cover itself has a broken corner and a shot gasket so I'll be replacing that too so my replacement motor doesn't see the same fate. Thanks for all the good info so far.

Three questions:

• Is this your first Mercedes?
• Where are you located?
• Did you find the scorched heater blower motor housing in the time between your first post and your second post? If so, welcome to the "obsession".

[meltedpanda]

I would suggest you do a bit of study on your KJET injection system. If you PM me your email I can send you some good articles, and welcome, lots of good folks here to help

[DanSel]

Originally Posted by daw_two

Three questions:

• Is this your first Mercedes?
• Where are you located?
• Did you find the scorched heater blower motor housing in the time between your first post and your second post? If so, welcome to the "obsession".

Yes, this is my first Mercedes and the first non-running car I've ever bought.

I'm in the Seattle, WA area.

Yeah, I found the scorched blower motor between then and now. I had removed the under hood cover for it toward the end of having ripped out the interior pieces to get to the under dash wiring. Having done some more posting and reading online I went back to look at it and noticed the scorch market and then got the flashlight down in the blower housing to see the scorching down in there.

[strelnik]

Originally Posted by meltedpanda

I would suggest you do a bit of study on your KJET injection system. If you PM me your email I can send you some good articles, and welcome, lots of good folks here to help

There's a ton of free stuff on the Kjet on the internet.

[compu_85]

If you want to check for shorts just hook a test lamp between the battery and the battery + cable. If something else is trying to draw as much current as the lamp would use normally it will glow brightly. If you use a headlamp and it glow brightly you know you have something drawing at least 45 watts with the key off, and that's probably a short.

-Jason

[t walgamuth]

It sounds as if you got a deal on this SL.

Good for you for rescuing it!

Pics!

[mespe]

1) change the oil
2) remove spark plugs and pull fuel pump fuse or relay (or allow fuel pump to push out all the old gas, then change fuel filter)
3) squirt a little WD40 into spark plug holes
4) crank engine until you get oil pressure

[ctaylor738]

Second the advice about the fuel. This is the most critical part of resuscitation. I suggest that you drain the tank, remove it, and have it boiled and coated. Replace any fuel lines that look suspect. Install a new filter. Unhook the fuel supply and return lines from the fuel distributor and connect them with a piece of hose. Then run the pump for a couple of hours by bridging 30 to 87 at the relay socket. Change the filter, reconnect the lines, and give starting a try.

I know this sounds extreme, but the reason you need to do this is to get every trace of sediment out of the fuel system before it gets into the fuel distributor and warm-up regulator. If you do this, you may avoid the "it ran fine for three days" syndrome.

Good luck.

[DanSel]

Well, I finally started the car today. I had to wait a few days for a specific fuel line I opted to change out. It was hard, kinked and cracking on both the inside and outside bend. I didn't feel like using the old only only to have to change it later. The old gas luckily had just gone off and varnished, not real congealing from anything I took apart. The old fuel pump was completely plugged on the inlet side though with a black buildup of filth over time. Surprised it even got any fuel through it before.

I changed out the fuel pump, fuel filter, a couple fuel lines that looked suspect, and of course drained the fuel tank. Happily there was only about 8-9 gallons in tank. Some nasty smelling stuff though. The smell is finally gone out of the garage only to be replaced by fresh smelling gas (under hood leak). Also put in fresh plugs and put plenty of PB Blaster followed by oil into the cylinders.

It started up on the third crank despite no throttle. The throttle linkage is bound up and not working right. There's a small fuel leak under the hood near the fuel distributor, but nothing major. Otherwise, nothing else noticeable as of yet.

So, I'm going to follow up with the other things I need to do to make it road worthy, but so far so good. Hopefully I can make the first drive in a week or two once I've gone through the brakes, changed out all the belts, checked the transmission and rear-end, etc. Looking good, I want my garage space back though.

Thanks everyone for your good info and support.

[t walgamuth]

Congratulations!

Saving old cars is a worthy cause. I have done it many times.

Sometimes when the project should have been classified even as a lost cause!

[meltedpanda]

change out all that rubber under the hood, best money you will spend, all the little fuel lines and such , years of high heat do them in

[DanSel]

So one of the obstacles I have left is the throttle linkage. I found where it's bound up - in the regulating linkage. According to my Haynes manual the pieces are called the 'gate lever' and 'angle lever'. These two pieces are mounted on the 'bearing bracket' with plastic bushings. This whole assembly was completely seized up. Couldn't move it at all. After a couple rounds of penetrating fluid, I could finally move the assembly by hand, but it was still incredibly stiff and not going to work.

I removed the circlips to start disassembling, but with pry bar pressure I was willing to exert without bending the pieces, I couldn't get them apart. I finally just took the whole assembly off including the bearing bracket to work on it on my bench. A couple more rounds of penetrating fluid and it's loosened up more, but I still can't get the pieces apart and it's still very stiff.

So, do I just take this whole assembly and put it in a bath of oil or something and let it sit to penetrate? Are these parts even available for sale? I haven't found a place that carries them. I don't know how loose this assembly should be, but I assume it should not be so tight and more free to move.