Apologies in advance for the length of this post. It's about problems related to a tear-down.

2007 R52 (Convertible S w/W11 engine). I acquired it with frothy/chocolate milky oil and a story about a cloud of smoke (steam, I'm guessing) that was driven for another 15 miles post incident. I got it after a brake shop (!) had already torn it down and removed the head, so the accessories and important bits came in a box on the passenger seat. I'm no mechanic, but I have done this same job on an R56 that turned out **** (until getting T-boned 3 weeks later....but that's a different story chronicled elsewhere on NAM).

I tore the rest of the engine apart, including removing pistons. I had no reason to believe there was an issue with rings, but my previous experience with the R56 had me do the same work twice after I discovered a piston had cracked and wasn't visible from the top side. So: new rings, crank journals, all new timing, new gasket set, and new coil, wires and plugs. I lapped the valves by hand and had the machine shop vacuum test. I had the head shaved and I replaced the valve seals. I set the timing and cranked it all the way around until everything lined up again. Re-assembled and it won't start. Sounds like there's an inkling but it's not that close. I have never owned an R52/53 so I didn't know what it would sound like cranking, but this surprised me with a "whirring" sound. It sounds odd. No metallic sounds, and nothing like a crunch or impact where there shouldn't be. I put a compression tester on it and there's no compression on 1-3, and 90 PSI on #4. I have a leakdown tester but am missing an attachment to hook it to the compressor, so that's currently a question mark.

I torqued the head to 40Nm+90 degrees with new bolts so I wouldn't think it'd be that far off with a new gasket and clean surface. Based on the total lack of compression on most of the cylinders, I'm assuming I got the cam in wrong somehow. Does that sound realistic? I can be an idiot sometimes, so we can't rule out stupid mistakes. Can anyone think of what I could have done wrong to get this behavior? I'll see if I can get the piece for my compressor to narrow it down with the leakdown, but won't be able to get any real progress until the weekend.

Thanks for any input.

 

Find TDC by feeling the piston crown with plug removed on any cylinder. Are the valves fully closed? There ought to be a wee bit of lash in the rockers, right? Just a thought to sanity check cam timing.

Cheers,

Charlie

 

OK with 1 & 4 @ TDC, the exhaust side is rock solid on 1. Intake is a little soft. On 4, exhaust has some space but intake is solid.

I thought 1 & 4 should always be the same? Even if I had the timing screwed up? Oh lawd, what have I done?

 

Takes two crank rotations to produce all four strokes. On one rotation the cylinder is transitioning from exhaust to intake, and depending on the overlap of the cam both intake and exhaust will be slightly opened. The exhaust will be closing, and the intake opening. The next time around, again a TDC, we're finishing compression and about to get power. At that TDC both valves should be fully closed. I would expect 1 and 4 to be taking turns, so compression on 4 would require a full turn of the crank after compression on 1.

I sympathize because the first engine I rebuilt gave me the same damned panic when I was fully reassembled and having trouble starting. A MG Midget from 1962.

Anyone else have a good sanity check for cam timing?

This turned up some nuggets...

Kind regards,

Charlie

 

I think I ran across most of those articles when I was assembling and many of them are simply marking the timing before disassembling and replacing parts, so the process is different. There's also a lot of confusion about TDC (I think it's irrelevant) and the line on the cam sprocket pointing to the back of the gasket cover which seems pretty...vague. Then the confusion around if it's at compression or exhaust stroke, which I assume is addressed if the links line up on the crank.

I feel like I followed the TIS process pretty perfectly EXCEPT maybe I had the tensioner in. I could be wrong, but I feel like it the links line up with the arrow/dots, that the tensioner wouldn't make a difference. But I think I'll yank everything out again and start from scratch. It seems like it gets more confusing the more I read.

If the crank turns 2x for every cam turn, maybe I AM 180 degrees off.

 

I assume you you setup the timing chain as in the 3 pictures of the TIS process...if so then you can't go wrong with the timing/cam.
What did you do with the block? honed? was the block deck checked for warp/trueness?
These engines have been known to have cracks in the cylinder walls...this is next thought after head gasket for the milky oil...crack into the water jacket

 

Man I hope it's not the block. I honed it with a simple tool with 3 long stones on a spring with a hand drill--I'm sure you've seen them before. Everything looked perfectly clean and considering the low compression is across 3 different cylinders I'm going to assume it's not that. I confirmed that the block was relatively straight with a straight edge while it was in the car and left it at that. It didn't show any major warping--not that would explain catastrophic compression issues across 3 cylinders.

Is there any chance the rockers could go on backwards or upside down or otherwise wrong?

 

Only if someone really wasn't paying attention when assembling the head. Pull the valve cover have a look and Post a picture.

One other possibility is that the rocker shafts are specific to intake and exhaust(rocker arm oil pressure holes in different locations) ...if they are installed incorrectly then there is the possibility/probability that there is poor oil pressure to the lifters and causing no/little valve lift.

Just some thoughts

 

I'll post a pic in a bit, but your post made me think. I took apart the oil pump when I had the timing cover off. I removed the inner planetary gears(?) as well as the spring and components in the cylinder labeled 6-10 here. I removed the sump as well, and replaced the o-ring. If I got any of that wrong, and there is no oil pressure, could the lifter not be filled sufficiently? I have to say, I'm unfamiliar with the way the captive lifters work in the rockers in this setup--I've never worked with this before. But if it needs oil pressure to fill and it's not getting it, I could see that causing this issue. The car was sitting for months while I worked on it and other things, so the pressure could have been lost. I definitely could have put the rockers back in a different order as well.

 

Related question: does anyone know of a way to test the output of the oil pump? Can I crank the engine with the valve cover off and see it squirting?

 

You could connect a hose with a gauge to the oil pressure switch and read the pressure you are getting.

 

here are pics of the valve train. So it hasn’t started since all of the work I detailed in the first post but I have cranked it 15-20 times for maybe 20 seconds each time. I would have expected to see more oil in the galleys. I also pulled the oil filter cap and that’s all but dry as well. Not quite but not dripping in oil like I would have expected. So I’m thinking it’s not getting oil and the lifters are soft, stopping the valves from sealing. Or am I just trying to talk myself into that?

regardless, I’m now waiting on a vibration damper pulley from Amazon because I busted mine. Everything else is off the front cover. So once I get that I’ll re-check the timing and pull the oil pump apart again. Any other ideas?

and does anyone know if I crank it now with the cam cover off, would I expect to see oil squirting into the valve train somehow? I’m ok with the mess if the test can tell me something.

 

Yes you should see oil coming out of the holes (you can see them the picture) in the rocker arms...yes it gets messy. Did you use assembly lube or oil when you assembled the head? Did you fill the oil filter housing directly before startup...dry startup is bad practice.

Replace the oil pump if there is no/little oil.

 

Head gasket flipped upside down blocking oil passage

 

Ugh, I hope not. I remember struggling with which way was which when re-assembling but then I found the oil passage and I'm pretty sure I got it right. Anyway to confirm that based on the excess/spillover portions of the gasket where it goes past the block?

I'm struggling a little with getting the vibration damper off this time around. Ruined one puller and had to go back to the well for bolts on the next one. Any secrets? Does heat help?

 

OK, I have the damper and timing cover off. I re-dissassembled the oil pump and it was put together correctly per realoem diagram. I had used assembly lube in the oil pump (maybe not required) and it was all gone, so I assume that the pump was moving oil through.

Yes, I did use assembly lube when I put the cam back together, so it wasn't dry. I didn't put oil in the housing though. Maybe not best practice but shouldn't cause a no compression issue....

I'll loosen the cam bolt and re-time per the TIS article, just basically aligning the arrows and chain links, but I'm not feeling like anything will be different if I simply re-assemble. Any other ideas about what I could have messed up to cause no compression?

 

I started another thread to troubleshoot smoke test results but quickly figured out (I hope!) what this issue was. Just in case another idiot like me comes along in the future with the same issue. See here. [see edit below, the spark plug tubes were actually a symptom of something else]

Basically, I must have slightly bent the spark plug tubes when I had the head off for cleaning, replacing the seals, machine shop work, etc., and the spring retainers were rubbing against the tubes, preventing the valves from closing. I bent them back and they look OK now. Not a lot of clearance there. And in fact I bent one far enough that it hit the cam lobe. Glad I found that before I put it back together. I'll start putting it back together and see if I can get it to go. But this perfectly explains the symptoms I had.

Thanks for everyone's input and help.

[edit 5/29/20] well I was partially right above. But the angled spark plug tubes were a result of installing the intake rocker arm bar (not sure what it's called, but it's the long bar that the rockers pivot from) backwards. It has indentations for the plug tubes when installed correctly, and pushes them back when installed incorrectly. Guess which way I installed it? Anyway, car back together and runs like a top]