15 replies to this topic

[EPcivic]

Well, I guess it was bound to happen eventually. After 4+ years of boosting, something inside my D15a3 motor decided to let go today at the Toledo National Tour. I noticed it started smoking a little yesterday before my last run. This morning after warming it up, I could hear a rattle when I reved it. I made one run and it sounded horrible. I thought for sure one of the rods was going to join me in the passenger compartment. Luckly, it held together through the run. The noise was a deep rattle, sounds like it's coming from the back of the motor, not up top. It was bad enough that the whole car shook when it was running under load. I decided not to run it anymore after the one run.

So, after getting home and unpacking, I decided that I'd try to figure out what's wrong. Here's what I've checked so far:

Compression check
- 75-80 lbs on all cyls cold. 80-90psi warm. 90psi when oil added warm. Last time I checked compression with this guage, I was getting 150psi. This time, the motor isn't tuning over quickly. It sounds about like it would with the plugs in, but they're out.

Leakdown check
I don't have a full leakdown setup, but using my compression tester and compressor, I applied pressure and listened - nothing odd.

Pulled valve cover
And looked at valves they are all still there and moving when told to.

Turned motor with torque wrench
There definately seem to be some tight spots when turning the motor. At the tight spots (plugs removed), it's taking 35+ ft-lbs to turn the motor, at the loose spots, it turns with little effort.

Watched crank pulley while running
I can definately see some runout on the pulley at idle. It's not much, but I can see it. When I rev the motor, the pulley moves slightly toward the motor and stops wobbling. This may be perfectly normal, I never really looked at it closely before.


My best guess at this point is that I've spun a rod bearing. Any other thoughts, ideas, things I could check easily??? I'd like to have it back together in 2 weeks for the Peru National Tour, but I'm not sure I can pull that off. Rod bearings would be easy enough to replace with the motor in the car, but I'm worried that one of the rods might be bent, and I'm not sure I could see that from underneath.

-Chris

[nivek2002]

definatly spun a bearing, sorry to hear it!

[CRXfanatic]

Time to drop the oil pan. Sounds like the crank bearings went if there's play at the pulley. If it's bad enough, you may have lost your thrust shims, too.

[criticalmass]

bummer...

let us know how pulling the pan goes... oil in water or vice versa?

with the compression numbers you mention on all 4, I'm afraid you may end up pulling the head too... might want to look at valves, tops of the pistons, head gasket, rings...

hope the damage is minimal...

[tjbizzo]

Sorry to hear it but you can't just replace rod bearings with the engine in the car. Well, at least not if you want the engine to last more than 30 seconds. Once you spin a rod or main bearing you will almost definitely have to get the crank and/or rod machined to have a usable bearing surface again. You will also need to completely disassemble the engine and THOROUGHLY clean out every single oil passage in the block, oil pump, head, and crank because the disintegrated bearing will leave tiny metal flakes everywhere. I don't mean just squirting some cleaner through the passages, but take out every plug, especially from the crank, and clean the passage thoroughly with a bottle brush. Yes I know it is a lot of work but if you don't do this you might as well leave your motor the way it is and and wipe your ass with a fistfull of $100 bills before flushing them. Same result with less time and effort.

[bigk3000]

i think its time for a boosted d16

[EPcivic]

Ok, so I took the oil pan off tonight and took a look inside. There were some bearing bits in the oil pan and pickup, but not very much. I've seen motors way worse. I pulled the rod caps off and found the problem. The #1 rod bearing spun. All the other rod bearings look fine. The cylinder walls look fine (as much as I can see from underneath). The rod doesn't look bent, and the spun bearings hadn't really worn all that much. Here are a few pics:

Here's the rod end and the crank.


The bearings, cap, and oil pickup. You can just barely see the metal in the picup screen.



Close up of the metal in the oil pan - not much really


As you can see from the pics, there is some scoring on the rod and the crank surface. I'm leaning towards spending the next few nights with some really fine sandpaper and polishing the crank and rod back to a smooth surface and just replacing the rod bearings and letting it ride. Of course, I'll clean everything I can get to, then flush the oil and filter several times once I get it running again. I just found a brand new set of rod bearings in my stash of motor parts, so I won't be spending anything for this "rebuild".

-Chris

[civtrx]

well glad to hear that it didnt work out to being as worse as you thought! Good luck and keep us posted!

[tjbizzo]

If I were a betting man (I am) I'd put a big stack o' cash on that engine owning you in the very near future. It's nothing personal, I'm just playing the odds. Glad to hear you're not sinking a lot of money into it though. Good luck and I'm cheering for you to win, but experience has usually shown the engine to be the victor.

[paul barela]

Glad to hear you're not sinking a lot of money into it though.  Good luck and I'm cheering for you to win, but experience has usually shown the engine to be the victor.

dito, i think just sanding the crank and putting i rod bearings will come back and bite you. But if it works out good, then thats coool. If your like me and strapped for the cash for a full rebuild this might work, but it would also be good to start saving for a full rebuild.

[criticalmass]

any guess on what's giving you the low compression numbers?

good deal on not losing the rod and that the crank looks usable...

[paul barela]

any guess on what's giving you the low compression numbers? 

having low compression on a turbo motot is usually means bad rings, but epcivic said that with oil (i'll asume this is a wet comp test)the compression numbers where the same. Then you could have burnt valves, that are leaking

[criticalmass]

both which, along with the headgastket and the tops of the pistons... are reasons I've been subtly trying to get him to pull the head... which is a huge hassle with the turbo gear on there I'd imagine...

[EPcivic]

Thanks for all the advice everybody. I took a look at the main bearings and they look fine, so I decided to try sanding the crank and rod. The crank looks pretty good. There is still one small area that has been pitted. I sanded it enough to be sure that the pitting is only downward - no raised surfaces. The rod looks worse. It is pretty scraped, but again after sanding the scrapes are all downward. I'm not 100% convinced this is going to work - actually I'd place my confidence level at around 50%.

The only explination I can think of for the low compression numbers was that the engine was not turning over quickly due to the tight rod bearing. I'm sure the motor needs rings, but it was making plenty of power right before it broke - actually, it was still making plenty of power even when the rod was knocking. The valves seemed to be sealing fine when I did the leakdown test.

Here's my logic for why I'm attempting such a ghetto fix: I have a complete motor sitting on my engine stand right now. It ran great when I pulled it from a wrecked CRX, but it has 220k on it. If I need to do a full rebuild, I'd start with that motor, since it doesn't have any unknown potential damage like bent rods, bent crank, etc, and the crank and rods wouldn't need to be turned to clean them up. I also have a completely rebuilt head that I've never used. Regardless of how this temporary fix works, I'm going to start a buildup using the other motor. I'd just like to have the time to build a slightly more boost friendly motor.

-Chris

[EPcivic]

Ok, I figure I'd give everybody an update on my progress. I've been a very busy boy the past few days.

I was all set to just throw fresh rod bearings in the motor and let it ride. When I started checking the tolerances, I didn't like what I was getting, and I also discovered that the rod and rod cap had grown slightly in width, making them tight against the side of the crank. This was obviously not a good thing, so I decided to pull it all apart and do the job right. The head and pistons actually looked pretty good. The rings were shot, and the valves weren't sealing too well either. I found a fair amount of shrapnel inside the block at the oil filter housing (past the oil pump). The rod in question was out of round on the big end by almost 0.010". Probably wouldn't have ran long.

I rebuilt this motor using the crank/rods/pistons from another motor I had taken apart 9 years ago and have kept in boxes. Every once in a while, it pays to be a pack rat. Tore it down Saturday AM, cleaned, honed, cleaned, then assembled the bottom end. Sunday I finished the assembly, using a fresh head I'd been saving as well. Got it back into the car Monday after work, and finished all the hook ups today and fired it up. So far so good. It fired right up and sounds great. Much quieter than before, and the intake has a really nice snap when you blip the throttle. I'm also pulling 6 lbs more vacuum at idle!

Wish me luck this weekend breaking it in at the Peru National Tour.

-Chris