View Full Version : B5 2.8 30V Cranks but won't start after timing

07-22-2013, 07:37 PM
Hi all,

Long time lurker/reader/searcher, first actual post. I've probably looked at every "2.8 cranks but won't start" thread on here and, alas, I have not found a solution to my problem. This is my first time owning/working on an Audi (or any German car, for that matter), but I have long and jaded mechanical history with my beloved Land Rover Discovery, the wife's Expeditions, and also some various Jeeps (not to mention any number of Japanese v-twins).

Brief summary - Following a rapidly-developing clicking from the rear of the passenger side valve cover (cam chain tensioner pads disintegrated), I endured a solid "thunk" on the highway at about 70 mph. Timing belt shredded (with less than 50k on it, if the PO's receipt was to be believed...which is questionable). Nonetheless, removed valve covers on both sides to find driver side camshaft head (where cam presses on) broken and passenger side exhaust cam teeth and chain ground up, presumably from plastic parts wedging in the cam chain. Installed boneyard cam assemblies on both sides, retimed with Audi cam sprocket tool and crankcase pin with crank at TDC, new timing components and belt, and back together. Yes, I realize valves are probably shot and I'm overly optimistic. But, I wanted to get it back together and do a compression test to see how many cylinders slammed into them before I pulled the heads and started work on the valves. This is, admittedly, the deepest I've been into an engine, although I did the head gaskets on the Land Rover not too long ago and found that to be relatively painless (beer helped).

Current situation - Everything is back together, checked timing, checked again, checked again, turned key, and...crank, but no start. When I turn the key, I cannot hear the fuel pump buzz. Fuel pump fuse is OK, relay is OK, voltmeter says I have ~4.6 with key turned and ~12.5 under crank, so it's getting power. Connected 12V source directly to fuel pump leads, and it pumps, jumper relay and it pumps, jumper the 373 relay next to the ECU and it pumps. So, it's not the fuel pump. I can "manually" make the pump do it's thing, turn the key, but still no fire. I can hear the throttle bottle alignment servo running when I turn the key (but don't crank), and it sounds like there's some sort of relay click coming from the ABS module (but I don't think that has anything to do with it). Timing kit came with a new coolant sensor, so that's in and connector is good. Picked up camshaft positions sensors and engine speed sensor (aka crankcase sensor) at the same boneyard, changed those, still cranks but won't start. So, I'm thinking something with the fuel injectors. Voltmeter says I'm getting signal there too (or at least Cylinder 5, which was the one I unplugged and check...I figure if one was getting it, they all were).

Interestingly, I cleared the codes from the timing belt incident (multiple misfires, camshaft position, blah blah blah), and I got not CEL codes - until I jumpered the 373 relay. Then, I got the P1237-1242 (fuel injector circuit open), P1392 (camshaft position sensor, open circuit or short to B+), P1422 (secondary air short to B+), and P1502 (fuel pump short to B+). Cleared those, cranked again...and no codes. That 373 relay seems to test fine, so I'm thinking it's something electrical "upstream" of that relay, before a firing signal can get to the ECU.

VAGCOM is on it's way. Yes, I know, I should have started there long ago, but I didn't. Hopefully that will help. But, if you have any ideas, please feel free to share!



07-22-2013, 08:04 PM
Have you done the compression test yet?

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07-22-2013, 08:10 PM
At highway speeds it's definitely possible to bend enough valves to prevent starting once it's back together.

07-22-2013, 08:36 PM
Compression test hasn't been done yet. I'm heading to O'Reilly tomorrow to borrow a compression kit, and I'll report back then. One other thing, I tried to spray some carb cleaner/starter fluid in the intake (past the MAF) to see if it tried to fire, and nothing. Same thing, cranks and has spark, but won't turn over. Looks like dillenger may be right. Guess I'll plan on heading back to the boneyard soon and look for a new set of heads. But, I'll wait for the VAGCOM and compression test before tearing back into the engine. If nothing else, it's been a good learning experience.

07-25-2013, 10:45 AM
At highway speeds it's definitely possible to bend enough valves to prevent starting once it's back together.

But bent valves aren't going to stop the fuel pump from working.

07-25-2013, 08:15 PM
Well, my local O'Reilly has their compression kit checked out at the moment, so no progress there, and I keep getting the peculiar "Too many communication errors to continue" message on VAGCOM when I try to scan the engine. But yeah, as 03a4b6ztk notes, that still shouldn't keep the fuel pump from running. And since I've got spark, shouldn't it at least TRY to fire? Especially with the starter fluid shot into the intake manifold? I guess that's where I'm most curious. I can where bent valves would make it run like crap due to no compression, but it should at least be combusting fuel, and that just doesn't seem to be happening.

07-26-2013, 04:36 AM
I wonder if the Crank or Cam sensor took a beating and crapped out? There would be your no spark and no fuel issue.

07-26-2013, 08:22 AM
Car will start with bad cam sensors (maybe not on the first attempt, but after ceasing to crank, then attempting again it should fire) and the crank sensor is in the bellhousing, far from any damage caused by a bad timing belt.

07-26-2013, 09:27 AM
Car will start with bad cam sensors (maybe not on the first attempt, but after ceasing to crank, then attempting again it should fire) and the crank sensor is in the bellhousing, far from any damage caused by a bad timing belt.

Understood but he also had damage on the chain side and gears and plastic every where, not just timing belt.

So thats what made me think of the crank sensor, but im not too familiar with the 2.8.

07-28-2013, 05:59 PM
Well, not much of a mystery anymore. Compression test shows zero compression on 5 of 6 cylinders (Cyl #4 had a whopping 80 psi...woohoo!). So, it looks like back into the engine I go. Off with their heads! Pretty sure the Pick N Pull still has a Passat 2.8 with the heads on it (although I don't know if they're grenaded or not) - does it make more sense to pull mine, order new valves, and have a machine shop rebuild them, or pull the ones from the boneyard assuming they're decent and just put those in? Any suggestions for how to get at the top bolt where the exhaust manifold bolts to the rest of the exhaust? I'm planning on just unbolting the manifold there and pulling it all out with the head, but those bolts look like a PITA to get to. The bottom two shouldn't be too hard from below the car, but that top one is just in a tight space.

Other than new head gaskets (already have new valve cover and cam tensioner gaskets), anything else that I should do when I'm that deep in there? Yes, I recognize this is a lot of work on a 14 year old car with a 150k on the clock, but the body and interior are in great condition, it drove and shifted great before the engine catastrophe, it's paid for, I have something else to drive while I'm working on it, and it's been a really good learning experience. Hence, I think I'm gonna keep going. Would also appreciate any thoughts on whether or not this makes sense at this point!

07-29-2013, 07:15 AM
Well if you go the boneyard route assuming there still good, you can still end up paying a machine shop to work on those heads.

I would just price everything including the bone yard heads(assuming no work) and also all the parts to rebuild your heads, and get a quote from some machine shops, making sure to tell them they are 5 valves per cylinder(I have heard of some shops not wanting to work on these heads).

Then make the best judgement for you cost wise. It may be easier in the long run to only have to pull one set of heads vs two.

07-30-2013, 09:32 PM
After two evenings worth of work, I'm nearly through the head pull on my A4. Only rear coolant pipes and head bolts remain. The exhaust manifold to exhaust pipe bolts weren't terrible, but thank goodness they weren't seized/rusted/on too tight - I don't think I could have gotten them off otherwise. Just not much room to work down there. The coolant pipes on the back of the heads look like they'll be a bit of a pain too, but at least there's just two each instead of three. Haven't talked to any machine shops yet, but unless the rebuild is ridiculously expensive, I'll probably just have mine done. Not sure I want to be pulling a second set of heads from the boneyard, especially for as hot as it is out there right now.

Anybody have any recommendations for a decent machine shop in the greater Salt Lake City area, and/or maybe what a reasonable price should be? Also, anybody know the inside diameter of that small vacuum tubing with the braided covering on it? Mine's pretty old and decrepit, so I figure I'll just go ahead and swap all of that out while I'm at it. I'll take some in to the store and try to match it up, but it would be better if I knew what it was supposed to be.

08-14-2013, 07:40 AM
So, just an update for the heck of it. Heads were dropped off at the machine shop last Friday. The head pull wasn't awful, but I elected NOT to pull a second set in the boneyard, because it certainly wasn't fun (and the boneyard is hot, and I didn't want to carry my tools in there, and they don't allow to bring a cooler full of beer in there with you...otherwise, I might have considered it). Visual evaluation says ~50% of the valves have some level of bend-age to them. Guy at the machine shop said he's seen better, but he's also seen worse. New head gaskets, manifold gaskets, secondary air pump gaskets, valve cover gaskets, head bolts, fuel injector o-rings, and some other sundry items are en route for a weekend's worth of fun when the heads get done. I can definitely see on two of the pistons where they struck the valves, but the "scouring" (for lack of a better word) doesn't look bad enough to warrant pulling the bottom end and replacing the pistons. I think it's more in the carbon buildup than anything else. I'll clean them off with some carb cleaner and go from there. All in all, this is probably more work and expense than the car is actually worth, but the body is straight and clean, the interior is nice, and I own it. And now I know a whole lot more about my engine than I did two months ago.

08-27-2013, 08:11 AM
The thread title really isn't all that applicable anymore, but for anyone following, I feel responsible to provide another update. Got my rebuilt heads back from the machine shop a week earlier than promised, and the guys in the shop were kind enough to let me borrow their Polydrive head bolt torque tool and one of those little widgets that helps you precisely measure the 1/4 turns when torquing (only cost me a sixer of Budweiser - their choice - which was better than buying them). If you happen to be in the greater Salt Lake City area, ask for Glen at Parts Connection in Sandy - nice guy and good with heads...Audi, that is. Total of 14 new valves, so could've been better but could've been worse. There were some impact marks/grooves on the pistons, but none that appeared to be significant and definitely no punch-throughs. I cleaned a bit of the carbon off them to verify, and measured the cylinder walls - still nice and round.

Spent parts of Saturday, Sunday, and Monday eve putting everything back together. Got new head gaskets, intake gaskets, exhaust gaskets, EGR gaskets, valve cover gaskets, head bolts, vacuum tubing, injector o-rings, etc from ECS Tuning and RockAuto (already had new timing components from the earlier work). Figured since I was that deep into it, I might as well do a thorough overhaul. Cleaned/degreased much of the engine bay. Reinstalled and retimed everything last night, and lo and behold, the old girl started right up! I did get a p0305 Cylinder 5 misfire code, and it ran a bit rough (probably because of the misfire), but that was at 12:30a, so I decided to wait until today to bother with it. Hopefully just a poorly-connected wire, or maybe a bad plug (I dropped the baggie of plugs at one point - wouldn't be surprised if one was affected), but after all that, I can live with trouble-shooting a cylinder misfire. Quite frankly, after all this, I was thrilled to just hear an engine running, even if it wasn't perfect on the first try.

From here, I'll reassemble the front end (my wife will be glad to have the garage back), drive lightly for a bit to start breaking in the new top end, and then do an oil change and maybe an engine flush. I was able to locate nearly all of the shattered plastic parts from the cam chain tensioner foot that failed (they were in the bottom corners underneath the cams), but I suspect there's still some small random pieces in the oil pan. Any thoughts on engine flushes in these engines? Anything else that I should look for on the misfire, and anything else I should be doing at this point?