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Super Moderator
4,459 Posts
Discussion Starter · #1 · (Edited)
I'm currently in the process of doing my timing chain, VANOS chains w/ tensioners, and VANOS service. And I think I may have inadvertently bent/kissed some valves.

I'm setting the cams at TDC in order to lock them with the pins. Everything is going smooth except for that Bank 1 exhaust cam. All the other cams received their pins without fuss, but that B1 exhaust cam seemed to be just a hair off and prevented the pin from going all the way down. The ABS module kept interfering with my wrench and I wasn't able to rock-it back and forth as easily.

Where the problems started:
To remedy the above I thought to myself that if I rotated the engine over until I was back at TDC, perhaps the slack in the chain would leave the B1 exhaust cam in a position where I could rotate it more precisely to get that final pin in.

I'm not sure how many full crankshaft revolutions I went through when turning the engine, but at some point I heard a pronounced POP over on Bank 2. Turning the engine over at that spot where the pop occurred was a bit stiffer than the peaks you feel when turning the engine over, but the engine did continue to turn beyond that point/pop in the CW direction. After my heart sank, I took a breath and started inspecting what could've caused it. At first I thought it was a tensioner snapping, but then I saw it, the helical gear on Bank 2 inlet cam had returned back to the IN position, all other helical gears had remained in the OUT position.

At this point I thought maybe the valves did touch a cylinder and the force cause that helical gear to pop back to the IN position. Since I could only assume the pop came from the helical gear, I continued with my original plan to get the engine back to TDC and try locking the cams again. That's when things went even more sideways. I don't recall everything I tried on my way back to TDC, but at some point in rotating the engine the exhaust valves started to contact the pistons and freeze/stop the engine (verified via endoscope). So after the first time the engine stopped I just accepted that if the valves are bent, that was that and I would need to remove the heads anyway.

Each time the engine came to a stop, I was able to free it up by identifying the cylinder making contact and rotating that exhaust cam CW. This worked very well, and I was actually able to get back to a spot where I could repeat the procedure to lock the cams at TDC. For now I'm going to proceed ahead with the work I had planned, I wanted to ask if there are any way I could check if the valves are bent without having to remove the heads.

Bank 2 Inlet Cam
Automotive tire Motor vehicle Gas Engineering Auto part

Bank 2 Exhaust Cam
Tire Wheel Crankset Automotive tire Motor vehicle

Bank 1 Inlet Cam
Automotive tire Motor vehicle Rim Automotive wheel system Tire

Bank 1 Exhaust Cam
Tire Automotive tire Motor vehicle Alloy wheel Wheel

P.S. yes those are score marks on the Bank 1 Exhaust cam for Cyl 1 (BMW ownership is the gift that keeps on giving馃榿:cautious:)

Where I'm at now, after getting everything timed again:
Wheel Tire Automotive tire Tread Yellow

Wood Gas Machine Composite material Metal

Motor vehicle Bicycle part Automotive tire Rim Gas

Edit: cleaned up some verbiage to clarify what I did in the beginning


Super Moderator
4,459 Posts
Discussion Starter · #4 ·
Valves touching pistons while turning the crank by hand should not result in bent valves. Crank resistance goes up and only if you keep going you risk damaging something. Valves are steel, they can withstand some reasonable force before bending. A running engine / piston hitting valves is a different animal.

Just my experience from reassembling other engines over time.
Thanks flacoramos,

Peter shared some similar reassurance; we discussed what I did and what could've caused that popping noise; but even if I was lucky and it was the helical gear popping back in, I need to do the leakdiwn test at a minimum. So I've ordered the gauge and I'll do the test once everything is all back together (chains, guides, vanos, & tensioners).

Unfortunately in the photos you can see there are score marks on the Bank 1 Cyl.1 exhaust cam-lobe. If the leakdown test is consistent across the cylinders I'll try changing just that one cam and starting the engine. If the leakdown shows a significant difference then it looks like the heads are off to PARTEE.

It'll be a while between updates since progress is at a snails pace. In the meantime I'll start writting up my ownership experience thread since I've got plenty of material at this point.

teaser pick:
Wood Bicycle part Gas Audio equipment Cylinder

Super Moderator
4,459 Posts
Discussion Starter · #9 ·
Did you coat them inside and out? I still have an Evolve set that I want coated. Probably by SwainTech.
I just coated the outside of mine. Swaintech White Lightning. Zircoflex is equally good, but across the pond.

Mine were also coated on the outside only, I actually took my set over to Swaintech in person and they/Mike seemed to be very quick to recommend against coating the inside of the headers. The Swaintech website claims they'll make the determination when it comes to coating the inside, and I got the feeling that they've had trouble getting all the way inside the more curved primaries so they know which type of headers to turn down. Also in the past the price between Swaintech and Jet Hot used to be about the same, but the quote I received from Jet Hot for the Ultra Extreme 2500 in the 2057-Titanium finish was >$1000, while Swaintech I think has only raised the price by ~$100.00: Automotive Coatings Price Sheet 鈥 Swain Tech Coatings | Industrial Coatings | High Performance Racing Coatings
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