Check list before first start

Specific conversations and info for the BMW E28 M5 and M535i.
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Syndrome
Posts: 128
Joined: Nov 23, 2021 3:46 PM
Location: DC

Check list before first start

Post by Syndrome »

Hello people. OK, so I think I’ve gotten to the point where there isn’t anything [known] left to do on my S38B35 engine. I’ve rebuilt the top end of the engine (put in a rebuilt head), adjusted the valves, put in a new radiator, water pump, thermostat, fan clutch, hoses, pipes, timing chain guide, all new gaskets and o-rings, oil, oil filter, flushed the block, and filled it with new BMW blue coolant etc. I set and verified the cam timing multiple times before putting on the valve cover, so I think it’s OK. My doubt is only because I’ve never worked on this specific engine type before. I’m ready to try to start this thing, but I’m not sure if there is something I should do before turning the key.

For example, will oil pressure build immediately, or should I try to get the pressure up before starting? If so, how do I do that? I hear that there is a fuel pump relay or fuse that I could pull…. Where is that? Seriously…. What should I do before turning the key? I’d hate to see this thing implode at this point, so I want to be sure I’ve done as much due diligence as possible before giving it a go.

Being paranoid may be a good thing right now. Thanks for your help.
austin8753
Posts: 1444
Joined: May 16, 2010 1:37 AM
Location: Portland, Oregon, USA

Re: Check list before first start

Post by austin8753 »

pull the main power relay before cranking the first time. the relay is in the glove box. crank the engine until the oil pressure light goes out, then reinstall the relay and try firing it. it might be good to have a friend or two listening to the engine as you are cranking it over, and perhaps it would be wise to have a fire extinguisher handy - you never know. good luck.
Syndrome
Posts: 128
Joined: Nov 23, 2021 3:46 PM
Location: DC

Re: Check list before first start

Post by Syndrome »

Thanks for that. OK, I’ll be holding my breath, praying for a good result. I just remembered one thing I still have to do (besides putting the intake air box on). There are two wires crossing the top of the firewall with connections at a bracket in the center. The bottom bundle is connected properly, but the top wire’s right hand side connector has fallen apart and the wire is disconnected. The wires inside are black, yellow and uninsulated silver. Do you know offhand what these wires do (what they power)? I don’t know how to post a picture here…
austin8753
Posts: 1444
Joined: May 16, 2010 1:37 AM
Location: Portland, Oregon, USA

Re: Check list before first start

Post by austin8753 »

those are engine speed and reference sensors. your car will not start without those connected. you'll want to buy those new and change them one at a time, so you don't get them confused with each other.
Syndrome
Posts: 128
Joined: Nov 23, 2021 3:46 PM
Location: DC

Re: Check list before first start

Post by Syndrome »

Thanks. It makes sense that the car won’t start then. I was not sure if it was because there was no fuel or no spark. Gave the intake horns a small shot of starter fluid and it ran for a second or two, so I guess that means the ignition works OK. That’s the first time this car has come to life since about 2010 or 2011, so that was a great experience, albeit very short. I’ll buy new connectors at the dealership now and see if it comes together from there.

I don’t hear the fuel pump running with the ignition switched on, though. I have never had a BMW before, so I don’t know what sounds I should hear. Thanks for any ideas.
Fanclutchnut
Posts: 113
Joined: Jan 05, 2021 7:32 PM
Location: Westchester Co NY

Re: Check list before first start

Post by Fanclutchnut »

Pumps only run when cranking/running and won’t run unless getting signal from one or both of those sensors(I forget)
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