(Image: Header Graphic)

Monday, June 24, 2024

Doug's Domain

Doug Vetter, ATP/CFI

Like what you see?

Donations to dvatp.com are now processed via Stripe. Like this site? It's easier than ever to show your appreciation.

Friday, October 27, 2017

Pre-Start Diagnostics

I arrived at my technician's bay this morning to find most of the work on the vehicle wrapped up. I earlier asked my technician to leave the airbox off so I could apply some paint protection film to the area under it that was previously rubbed so hard by the airbox that it left an imprint of the embossed part number in the shock tower. Naturally, I didn't want a repeat of this process so I cut a small section of film and applied it.

My technician had already put six quarts of Amsoil SAE30 break-in oil in the engine and several quarts of the provided Redline D4 ATF in the transmission and torque converter so the first task was to connect the diagnostic system and verify we didn't have any faults. That scan revealed two items: first, a fault with the muffler valve solenoid -- a known issue with this car since I removed it when I switched to the M3 exhaust -- and second, an unresponsive pre-cat O2 sensor heater. My technician ran a few more tests and briefly disconnected the sensor to come to the conclusion that we'd need to get a new sensor. But, he was quick to add, it would not prevent the engine from running.

Engine Start

Once the airbox was installed there was only one thing to do -- start the engine. Prior to connecting the battery yesterday my technician removed the fuse that protects the fuel pump circuit. The intent was to use the starter to crank the engine over a few times without it firing to help prime the oil pump, fill the oil galleries and get enough oil past the check valve in the head to minimize the time following ignition the top end was without oil.

The first few cranks were uneventful, and that alone was a relief. However, even after 3 cranks of about 5 seconds each the oil pressure annunciator in the gauge cluster remained illuminated. We gave the starter a breather for a few minutes and then duplicated the process but the oil pressure light refused to go out. So we stopped and pulled the oil filter out of the housing to see if any oil had made it to the filter. We found it bone dry; not a particularly good sign. My technician took the last (7th) quart of oil I gave him and carefully poured it into the housing, outside of the central column, and then reinstalled the oil filter. It was around this time that I realized I was pacing around the car like an expectant father.

(Image: The team responsible for first start of my new M52)

With the filter secured in the housing we cranked the engine a few more times. The oil light stubbornly remained on, so we then removed the oil filter again to find it completely saturated. Confident that the pump was doing its thing, but just having trouble pumping enough to fill all of the galleries and build pressure, we decided the only thing to do was to install the fuel pump fuse and give it a shot. The plan, of course, was to shut the engine down if we didn't see a pressure indication in 5 seconds, which is the typical period of time that it will take to build oil pressure following a routine oil service.

After turning the key to position two and waiting a few seconds for the fuel pump to build pressure, he turned the key to the start position. The engine turned over freely for about three seconds and then fired. He didn't see oil pressure within a few seconds so he shut the engine down. He then started the engine one more time and this time the oil light went out almost immediately. The engine ran at this point but we heard a rather loud sucking sound that we ultimately traced to a hose that was disconnected from the bottom of the intake boot. This is, of course, the hose that delivers air to the ICV, which controls idle air flow below 20% throttle. With that installed properly we once again turned the key. The engine fired and settled in a smooth idle. Almost immediately some smoke began to waft from the headers but that was expected as the penetrating oil used to remove them three months ago began to burn off.

The fact that the engine started and idled smoothly and quietly for a minute or so before we turned it off provided several very important datapoints:

  1. there was obviously no piston to valve contact.

  2. the engine is timed correctly.

  3. the vanos was installed correctly.

  4. there were no collapsed lifters.

Transmission Top Off

The next step was to top off the transmission. This of course requires the engine to be running and is easiest to do with the vehicle on the lift, so my technician suggested I hop in the car and move the gear selector while he pumped fluid into the fill hole. So up on the lift I went. While the engine idling, on cue I put my foot on the brake, switched the transmission into reverse and left it there for a few seconds before shifting into drive and waiting another few seconds. I then put it back into reverse, and then into park. I repeated this process about four times as my technician topped off the fluid.

On cue I shifted it into drive and reverse while letting my foot off the brake in each gear to allow the wheels to spin for a few seconds. This confirmed the basic operation of the transmission. My technician managed to pour the remainder of Redline D4 ATF I provided into the fill hole (a total of 9 quarts thus far) with no signs of dripping fluid, which indicated that the transmission was still a bit thirsty. My technician suggested it might take as much as 10-12 quarts to fill everything including the lines and cooler so he reinstalled the fill plug for now and lowered the lift. Once back on planet earth I turned off the engine and got out.

Cooling System Top Off and Bleeding

A bit later we started the engine again as required to bleed the cooling system. Initially we allowed the engine to idle and removed the expansion tank cap to fill the system while the bleeder screw was loosened. As coolant was slowly added my technician asked me to rev the engine to 1500 RPM and I did so as he watched yet more bubbles exit the bleed screw. Another minute or so later I returned the throttle to idle and noted that the coolant temperature needle was now pointing at the 12 o'clock position, exactly as expected.

Test Drive Postponed

Unfortunately, I could not take the car out on a test drive today because I need to order more ATF and we need to install the O2 sensor so I can rest assured that the engine will use the normal fuel maps on my ring-seating runs. We also found that the alternator cooling duct had broken at some point so I had to order those components as well. All of the parts and the ATF should be here Monday so the car will spend one more weekend perched on my technician's lift. And it's probably just as well, since we're supposed to get a hell of a Nor'Easter here on Sunday.

I'm not exactly out of the woods yet with this build but today was a very good day.

Next Up

If all goes as planned I should be able to bring the car out for a test drive on Monday. This will be somewhat complicated by the need to remain as stealthy as possible on the road because the inspection sticker has expired and yet I can't take the car to inspection until I have completed enough drive cycles and the emissions control system reports all systems "ready".