Trying to get my '86 running again after sitting for 10 years

[jdmackes]

So my '86 635csi has been sitting in my garage for the last 10 years or so and I'm starting to get motivated to get her running again. I've been having a hard time finding information online (lots of dead links all over the place), so I thought I would post here and see if anyone had some advice for things to start out with. She'll turn over but not start, so I think I'm going to start with pulling the gas tank and making sure that's cleaned out and see if the fuel pump has seized. Additionally, my clutch pedal used to be very heavy to push down, but now appears to have no resistance at all so I'm not sure what would have happened there. Any advice or pointing me in the right direction when it comes to manuals would be great, thanks!

[jbd5015]

Purchase the Bentley Manual for an E28 5 Series.

There is a tremendous amount of information and troubleshooting guides throughout the manual. No internet required.

Im guessing you lost fluid in the hydraulics for the clutch. Most likely a rotted seal or hose in the system. Check the brake fluid reservoir and make sure the fluid level is high enough for the clutch suction line.

Crank and no fire can be a list of issues. If the fuel tank was anything less than completely full, assume its got rust. Pulling the tank is definitely a good start!

[RSheiman]

Well, you seem to imply there may be 10 yo gas in the tank so yes, drain, take a peek, check pressure at the fuel rail, check for spark. Look underneath for puddles, I bet your slave cylinder crapped out and there is brake fluid on the ground and and the reservoir is low.

[sienayr]

If you find corrosion in the tank, I recommend the por15 fuel tank cleaning and coating system, will take care of corrosion for good. A quick check for corrosion is pull the fuel pump and check for sediment on the intake screen.

[DesktopDave]

Good thing you're getting it back on the road. I'm guilty of the same thing...shouldn't be too much trouble.

+1 on the fuel. Ten year old fuel, especially if it's an ethanol blend, is likely to accumulate a bit of water in the bottom of the tank. Hopefully that's your only problem. To start, I'd pull the lift pump out of the tank and see if there's any water in the tank sump. A little drain & fill would be ideal. I like to use one of those cheap fluid pumps to suck all the fuel out. Looks like HF just released a battery powered fuel pump I was considering. I had good luck with their really cheap manual pump, although it's a lot of work and falls apart sometimes. Our fuel tanks do have a small drain plug but I'd leave that alone. It's a small socket bolt , like a 5mm, with a metal gasket. Be prepared for a mess, it's difficult to funnel that into fuel cans...

There's a really great step-by-step guide I always use for working through Motronic running problems. The web site is difficult to find, here's a direct link:
https://hpsimotorsports.com/blogs/te...n-tech-article
I actually printed out a copy a while back to leave in the glovebox. It's that good!

You have an '86 (great year, BTW), so you've most likely got an M30B34 running the first version of Bosch Motronic (1.0). I'd guess you're not getting a signal from the bell housing sensors or the flywheel pin has sheared off. If that's true, your ECU (Bosch calls them a DME) won't be powering up the fuel pump. It's a common problem. Once I've tested those, I usually just jump the fuel and main relay sockets with some short segments of wires to eliminate them as a problem. They're typically clipped to the outside of the fusebox. Ordinarily, I'd have directed you to my blog post on jumping those relay sockets, but it looks like my hosting company is down. Sorry about that, I'll update when I know more.

The clutch likely just has a fluid leak somewhere, or a bubble in the line. It's also possible the slave cyl has a blown seal or it's fallen off the clutch fork. The clutch master cyl has a feed hose coming off the brake fluid reservoir, check to see if there's enough fluid in there. Report back on your findings...

- - - Updated - - -

Looks like my site is back up! Here's a link to the jumper article.

[e24mpwr]

Good thing you're getting it back on the road. I'm guilty of the same thing...shouldn't be too much trouble.

+1 on the fuel. Ten year old fuel, especially if it's an ethanol blend, is likely to accumulate a bit of water in the bottom of the tank. Hopefully that's your only problem. To start, I'd pull the lift pump out of the tank and see if there's any water in the tank sump. A little drain & fill would be ideal. I like to use one of those cheap fluid pumps to suck all the fuel out. Looks like HF just released a battery powered fuel pump I was considering. I had good luck with their really cheap manual pump, although it's a lot of work and falls apart sometimes. Our fuel tanks do have a small drain plug but I'd leave that alone. It's a small socket bolt , like a 5mm, with a metal gasket. Be prepared for a mess, it's difficult to funnel that into fuel cans...

There's a really great step-by-step guide I always use for working through Motronic running problems. The web site is difficult to find, here's a direct link:
https://hpsimotorsports.com/blogs/te...n-tech-article
I actually printed out a copy a while back to leave in the glovebox. It's that good!

You have an '86 (great year, BTW), so you've most likely got an M30B34 running the first version of Bosch Motronic (1.0). I'd guess you're not getting a signal from the bell housing sensors or the flywheel pin has sheared off. If that's true, your ECU (Bosch calls them a DME) won't be powering up the fuel pump. It's a common problem. Once I've tested those, I usually just jump the fuel and main relay sockets with some short segments of wires to eliminate them as a problem. They're typically clipped to the outside of the fusebox. Ordinarily, I'd have directed you to my blog post on jumping those relay sockets, but it looks like my hosting company is down. Sorry about that, I'll update when I know more.

The clutch likely just has a fluid leak somewhere, or a bubble in the line. It's also possible the slave cyl has a blown seal or it's fallen off the clutch fork. The clutch master cyl has a feed hose coming off the brake fluid reservoir, check to see if there's enough fluid in there. Report back on your findings...

- - - Updated - - -

Looks like my site is back up! Here's a link to the jumper article.

Your site is back down

But THANKS for the very-awesome Motronic article. I PDF'd that puppy and it went straight into my good M6 stuff folder. It will probably help me now as I can't get Cosmo to run. Will sorta-idle, but can't take throttle or any load.

[jdmackes]

Thanks to everyone for your advice! Does anyone have any experience with Por 15 tank coating? It looks nice, but it won't eventually flake away or become brittle? I was planning on just using evaporust and getting all of the rust and gunk out of the tank that way; should I go with their system instead?

I'm starting to price everything out as I feel like I'm going to have to replace a lot of parts, but so far it doesn't seem too bad honestly. If I have to start replacing a lot of brake parts (aside from the hoses) then it'll get expensive, but otherwise it seems like this won't take too much to fix up (which will make my wife happy). Thanks for the info again and I'm sure I'll be asking a ton more questions as I get started in a couple of weeks!

[jdmackes]

Purchase the Bentley Manual for an E28 5 Series.

There is a tremendous amount of information and troubleshooting guides throughout the manual. No internet required.

Im guessing you lost fluid in the hydraulics for the clutch. Most likely a rotted seal or hose in the system. Check the brake fluid reservoir and make sure the fluid level is high enough for the clutch suction line.

Crank and no fire can be a list of issues. If the fuel tank was anything less than completely full, assume its got rust. Pulling the tank is definitely a good start!

So the E28 is close enough to the E24 to not make a difference? I just want to make sure before grabbing it, thanks! (and yeah, looks like I'll probably have to replace the clutch master and slave cylinder, but they're pretty cheap)

[RSheiman]

Yes for most needs and certainly for mechanical repairs.

Por 15 should be used if your tank is shot, ie beyond surface rust. I found Evaporust worked well for surface rust only. Por 15 will handle pinholes and deep rust and seal all seams. I and tons of others think the kit is awesome. The coating will outlive you and your car. Never seen or heard of any issues.

BTW I bleed the slave cylinder before I reattach it to the car. The hose is flexible so placing the nipple non-dependent is easy and quick.