Tricky crank no-start problem

[80stech]

The intake is indeed puffing

The noise is coming from the valves the problem isn't the intake itself. The valve timing is probably way off. Is there a chance that the intake and exhaust cams are mixed up ?? Do you not have access to running engine to practice doing a compression test ??

[DonaldFoss]

I took the belt off, rotated the engine until Cyl 1 was top dead center, checked the timing mark, and it was spot on—then I realized that it had nothing to do with the cam timing, only the crank orientation. I took the belt off and everything. Sigh.

I pulled the plug for Cylinder 1 and ran 3 compression tests while watching the spark plug. On a whim, I tested with the new plug the first time then the original working plugs the 2nd and 3rd times. I recorded it all. Unfortunately, the dial for the compression gauge has a glare on it for #2-3, but doing a 4-crank, by ear anyway, compression test, I got 140, 145, and 148 PSI. For the first two, I didn't touch the throttle like I should, which is why I did the 3rd, but since it was so similar, I didn't redo it anymore.

Click the video link: Compression/spark plug tests 1-3 video

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I threw the videos together and added captions, but I didn't take the time to align them and add a soundtrack. You can hear a little of the music I was listening to in the background. I don't want a bill from the RIAA.

The spark looks very similar across plugs and tests. The light in the tester is whitish at first, then reddish. That indicates to me that my coils aren't producing enough voltage. I have a spark gap tester arriving tomorrow; I'll see what it says. Since these coils were working correctly, even if they are weak, I don't think that's the reason it won't start at all or even turn over.

I'm leaning toward compression because I did a leak-down test before reinstalling the engine. It was abysmal. If I put air pressure in the spark plug hole with both valves closed and the cylinder at the top dead center position, then sprayed carb cleaner on TOP of the valves, the carb cleaner bubbled until it was gone after a short while. It did this in EVERY cylinder. Now, I'd never lapped valves before, much less taken apart an overhead cam head, and VANOS tore everything down and put it back together. Lapping valves doesn't seem hard, but clearly, I must have done something wrong because the best the leak-down ever got was 20%, and most cylinders retained 0%. Listening to the engine during the leak-down test, the air was clearly coming out of the valves, usually on the exhaust side, but some on the intake side--and some on both. I could hear no air sounds from the crankcase or oil dipstick.

[DonaldFoss]

Originally Posted by 80stech

The noise is coming from the valves the problem isn't the intake itself. The valve timing is probably way off. Is there a chance that the intake and exhaust cams are mixed up ?? Do you not have access to running engine to practice doing a compression test ??

I could do compression tests on my Hondas. I've not spent much time under the hood of those; they just run. I did several compression checks on this engine when it was running before removing it from the car to get a baseline. The instructions said to disconnect the fuse for the fuel pump, attach the gauge in the cylinder spark plug fitting, crank for 6-10 seconds with the throttle fully open, and then record the reading. That is pretty straightforward. I will get an extension for the hose going to the compression gauge to see it easier from within the car. It doesn't have standard fittings.

While anything is possible, it is unlikely I got the intake/exhaust backward. I've spent a bunch of time in Germany, enough to be barely conversational in German, and you also see Ausfart and Einfart at every interchange on the Autobahn. I wouldn't have thought the A stamped on the cam meant it went first, not to mention the ends of the cams facing front are different on the intake and exhaust sides--I didn't think you could mess them up. When I pull the head off, I'll double-check this. I know I originally put my mains caps on backwards before catching that...

[X5chemist]

Uneven cranking is a sign of uneven compression. An oscilloscope wave form on a battery cable would show it.

[80stech]

140-150 is fine especially if the cylinders are wet with fuel (is fuel good??) it would be nice to do all cylinders the same way to be sure but I guess we can assume they are fairly even from the 10 second compression test. Plugged exhaust (is that possible?) will cause the puffing sound and the no-start but then there should be some other things going on as the pressure builds. I would still say there is a problem with the valve timing though, maybe get the timing instructions from a different source and re-check that. Spark looks good but for sure better to verify that with the gap tester.

That being said, I doubt the lapped valves are not going to last so they will need to be redone at some point anyway.

[DonaldFoss]

Originally Posted by 80stech

140-150 is fine especially if the cylinders are wet with fuel (is fuel good??) it would be nice to do all cylinders the same way to be sure but I guess we can assume they are fairly even from the 10 second compression test. Plugged exhaust (is that possible?) will cause the puffing sound and the no-start but then there should be some other things going on as the pressure builds. I would still say there is a problem with the valve timing though, maybe get the timing instructions from a different source and re-check that. Spark looks good but for sure better to verify that with the gap tester.

That being said, I doubt the lapped valves are not going to last so they will need to be redone at some point anyway.

Thanks for the feedback and ideas, 80stech. I learned how to work on cars starting in the early 80s, first on a 52 Ferguson tractor, then my 70 Chevelle. My father said I couldn’t drive it until I knew how to rebuild it and he taught me how. 3 years and 15”x12” Kelley tires later, I fubared my transmission, and he said “you break it, you fix it.” With no lift or even a floor jack, I used wheel ramps, pine logs and 2x10 boards as levers. I rebuilt a Turbo 350 I had bought cheap and broken, put in a shift kit, bands and valves and put it in the car. Dad had to correct the transmission cooler lines though… Ah, memories.

I drained all the fuel from both sides of the tank at the fuel senders last weekend and put 3 gallons of fresh pump 93 octane gasoline in.

Cylinder 1 is the best. There was about a 25 PSI drop yesterday with a 4 crank (4 flashes of the spark plug light) test versus the 10 second test. I only did 1 cylinder last night. If that drop persists, I’ll have the following, cyl 1-6:
- 145 PSI
- 120
- 105
- 125
- 100
- 110
Note that only cylinder 1 is an actual measurement. The others are based on the previous measurement with a fixed offset. I’ll remeasure all again tonight if it’s not still raining. Severe thunderstorms right now.

There is a turbo on a new cast exhaust manifold, and I built a new 2.5” down pipe to a Y-pipe, 2 new cats under the frame, to the old X muffler to the final individual end mufflers. I pre-oiled the Turbo plus it has a high pressure oil feed tapped off the Vanos oil feed at the sending unit. The exducer spins freely, don’t know about the inducer. The new cats aren’t clogged, and I pushed compressed air through the X and final mufflers as part of cleaning and ensuring they were good to go. I didn’t measure output, just that air flowed and that I could feel air coming out each pipe. Air compressor puts out 5.3 SCFM/11.9 CFM at 40 PSI. I don’t know what it’s rated for at 1 bar.

I’m really curious why it seems as if I’m pressurizing my intake with the throttle body connected to the MAF then open air. With my N55 intake, it builds pressure until it forces it out of the vent on my catch can.

The engine has not ever started with the turbo on it, or after my rebuild. I’m desperate enough to pull the turbo off, or alternatively I can put a hater pipe out the back of the turbo and force the waste gate open to validate exhaust issues.

The original exhaust valves looked burnt, and had what would appeared to be Viking Runes around the edge. Kinda cool actually. The intake valves looked virtually new after being soaked in Chem Dip and buffed with a bronze brush, then wool with polishing compound, then plain wool to remove any leftover compound. I bought new, moderately high end (not the most expensive) exhaust valves from Bimmerworld and reused the intake valves I’d cleaned and polished. I tested the spring compression, they were all good, so I used the original seats, guides, springs, keepers, etc. They all took a Chem-Dip bath overnight too. I put Ultraslick in the guides when inserting the valves and ensured they went up/down and spun freely, and that there was no lapping compound left. Before I put oil in the engine I checked the pan and it had a bunch of Ultraslick there. I found that somewhat amusing.

In a way I’m surprised it makes much compression at all since every valve leaks. I’ve never had to deal with leaky valves before. Is this typical? I still don’t know if the leaky valves are the valves themselves or the valve sleeves. If it’s the sleeves, I’ll get a used head rather than pay for resleeving right now. I won’t port the head this time until I know the engine runs first. I highly doubt the porting affects the starting.

I got the gap testing tool today, so I’ll do that once things dry out. I’m pretty crazy but even I don’t want to play with 30k volts in the water—it’ll jump too easily.

I found a set of Dragon Fire and Mishimoto coil-on-plugs. If the gap test is bad enough I’ll order one of those. I want a longer spark if possible to handle the forced induction.

On timing and stuff, I used Wossner’s guide for rings, the Project Crankshaft guide on E46fanatics, the cam removal/installation/timing guide from German Auto Solutions. The GAS guide was really good, with plenty of pictures. They make a very nice tool for working with the cams. I can look in INPA for their timing procedure. I saw it once before but thought the GAS guides were more complete and made more sense. I think Pelican has a guide too.


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[DonaldFoss]

Originally Posted by andrewwynn

I pay the $1. It's worth it. No ads


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On a per month basis, you have a good point.

[DonaldFoss]

Originally Posted by X5chemist

Uneven cranking is a sign of uneven compression. An oscilloscope wave form on a battery cable would show it.

I know the compression is uneven, but I’ll put my o-scope on it for fun to see what the waveform looks like. I paid for the thing, have to play with it every now and again or it gets lonely.

[DonaldFoss]

I pulled my notes and when looking for the GAS cam removal/installation/timing instructions, I found where I printed out the ISTA instructions for timing and I have a check mark by each step, so I performed those timing steps, even pretensioning the timing chain adjuster to 0,7 Nm. Only my 1/4” torque wrench went that low.

[80stech]

I guess I used a double negative but what I meant to say is that the lapped valves won't last. If you get the valves done at a good shop they will probably cut the seats instead of grinding which leaves a sharper edge to seal better and a less likely to be affected by carbon build up but also often leaves a slight burr or ridge where the cutter stops causing even more of a valve leak than what you are talking about, enough to see light through but not enough that the engine won't start. If the rest of the cylinders are as low as you are predicting that is a problem. I think the only way you can get a pressure build up in the intake is if there are some serious valve timing issues or the exhaust is plugged. Even with leaking valves there would still be a full stroke of valve open suction for every stroke with bit of pressure leaked by. I don't know what you have for a cccv or how you have the intake is connected to the crankcase but it might help to check/disconnect that for further clues.