Guess what's wrong with my motor..

[masterbeavis]

Spun a bearing coming home, did not run it too long, parked it, have a nice video of the klack klack klack.

Motor has unknown miles, last tank of fuel was 44.7 mpg.

Compression:
Was: 560, 400, 430, 460
Now: 500, 400, 480, 440

Rolled in good used bearings, .036mm of clearance (obtained with plastigauge)
Knock at idle has gone away, you can hear a popping in the exhaust.

[theman53]

They are tough, you should be able to get it ground if it is needed. I would have it inspected if you can. sorry but I don't have one.

[ORCoaster]

Lucky day for both of us.  Give me a PM and I will shoot some pics of what is in the shed and you decide.  Buy or Bye...

I am only rebuilding the head of the engine, Block went north to Portland in exchange for labor on the head but he didn't need the crank.  Pistons shot but rods OK.  What else might you need.  I have nearly a complete 1.6 N/A and I am willing to part out most all of it to keep collecting more. 

[CRSMP5]

well which bearing spun?

main = block

rod = rod

i have polished cranks before in car with emery paper.. never had a issue.. but if its really pitted.. seeing copper imbeded in steel.. its crank time..

what year crank? the 11mm blocks have odd crank pully with real key vs later ones that aaz breaks.. but that style can be modded for tdi style..

[masterbeavis]

Took it apart last night, crank looks fine, #3 rod bearing had damage. The bearings did not look worn enough to have this bad of a knock.

[masterbeavis]

Motor is of 82-84 vintage, 12mm hydraulic, CR code on block

[CRSMP5]

  hydro came out in 85..

what was your oil pressure like before the knock? turbo or not? #3 rod is usually a fast failed oil pressure issue.. spinning #1 or 2 mains is lazy did not keep oil up to snuff.. they get starved of a few psi the sendors do not catch..

so queston is why all of sudden oil issue..

[theman53]

I figured. They are forged and harder than a woodpeckers lips. If you mess one up usually you spin the bearing and keep going, and going, and going and then you need to cut the crank down. I did have a crank that was too bad to cut, but it looked like the PO let it hammer on a trip to CA and back before pulling the engine. The #3 had a paper thin rod bearing and the rod and crank were discolored due to heat. Even then if I could have gotten a bearing I would have had a shot, but it would have taken .050" or more. At that point I got another that is fine.

[Toby]

Usually you won't get a rod knock until the bearing spins or maybe just before. A good way to check is to use the "babbit beater" technique. On the stove bolt Chevys of old, with poured babbit bearings, (no inserts) you would remove shims until you could move the rod big end sideways but not up and down. As long as you couldn't feel and up and down free play they wouldn't knock. The same is pretty much true for modern engines. Try putting the worst one back together and give it a try. (Or if you are one of those pussies that wants to do it he right way, you could plastigage it.) ;<)

One other thing to remember is that problems on the other end of the rod can make rod knock-like noises as well. A bad wrist pin bushing or  a cracked piston can make sounds that are hard to tell from a spun rod.

[masterbeavis]

I will find out if the top end of the rod is bad tomorrow when I roll in new bearings. I seen alot of glitter on the #3 journal when I removed the bearing.

I will be a sissy and plastigauge the new bearing.

I don't know what the oil pressure looked like prior to it dying, no gauge hooked up. I could swear at times the oil light would dimly illuminate, but this car did alot of weird things. It had fresh Delo in it.

I did notice some bluing on the crank around the edges where the rod journals make contact. Not a lot to concern me, but it is there.

[masterbeavis]

Oh, forgot to mention I goofed up a 4-5 shift and wrapped the motor up real tight for two seconds or less about 20 miles before I got home.

19.99 miles later I am coasting 1 house before mine and I hear a playing card in the spoke of a bicycle.

[masterbeavis]

The knock at idle went away, but you can hear there is a dead cylinder in the exhaust (PUTT PUTT PUTT PUTT), it doesn't purr right, and you can hear the obvious knock above idle.

I ran a compression test before it blew up and after.

Was: 560, 400, 430, 460
Now: 500, 400, 480, 440

I don't know how to explain compression numbers above 480, or a 50# increase in the one cylinder  My book says 480 Something is a new motor, maybe alot of carbon in that particular cylinder?

No coolant in the oil, no oil in the coolant, coolant is where I filled it last.



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[theman53]

Sounds fine as the numbers go. I would wonder about the head maybe?

[Toby]

No, its not fine. There is too big a difference between 500 and 400. When was the last time you adjusted the valves. (I presume its a mechanical head.) The very high reading is likely due to carbon in that cylinder. Is the one with the compression increase the one with the loosest rod bearing? If not this is likely pilot error. The engine needs to be warm and the battery hot, (preferably with the battery charger on it) and the test needs to be done for a specific number of beats, not just until the gauge quits moving.

[masterbeavis]

It's a hydraulic head, the cylinder with the high compression has a collapsing lifter.

First test was on a cold motor, second test was ran after running the motor for 5 minutes or so(not up to temp)

I did not count revolutions, but did not crank forever on each cylinder either. I removed all injectors at once both times for testing. 


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