VWDiesel.net The IDI, TDI, and mTDI source.
Engine Specific Info and Questions => IDI Engine => Topic started by: masterbeavis on April 24, 2013, 04:17:57 pm
-
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.
-
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.
-
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.
-
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..
-
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.
(http://img.tapatalk.com/d/13/04/25/8y4a3ava.jpg)
-
Motor is of 82-84 vintage, 12mm hydraulic, CR code on block
-
;D 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..
-
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.
-
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.
-
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.
-
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.
-
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.
Sent from my iPhone using Tapatalk
-
Sounds fine as the numbers go. I would wonder about the head maybe?
-
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.
-
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.
Sent from my iPhone using Tapatalk
-
High pressure in #1 carbon or valve related. Low in #2 is trouble as not very balanced across all 4. Perhaps a bad seat on head for either or both valves. Otherwise the 480 is spec on new motor. Gain likely due to oiled rings the second time?
-
Update:
I reran compression. I allowed 5 revolutions on a cold motor.
450
380
420
440
Before putting it back together I cranked the motor for a while to see how the lifters pump up. 3 are weak, over 1/8" deflection. I put it back together as-is, still had the knock. This time I cracked injector lines once running to isolate the offending cylinder, put in another injector, the noise went away! It does not run right however. It's low end torque is gone, you can feel the misfire. I need my injectors gone through and lifters.
Sent from my iPhone using Tapatalk
-
A stuck injector sounds just like a rod knock.
Compression test should be done on a warmed up engine and the number of revolutions DOES NOT MATTER. You should keep spinning the engine for a given cylinder until the pressure no longer rises on the gauge. That's usually a heck of a lot more than 5 revs.
-
I've ran the compression test 3 times on this motor, twice cranking till the end of time and getting the first two set of numbers. I'm not going to warm a car up with a suspected spun bearing to do a compression test. If I was doing the test wrong, the numbers cold are still high enough to convince me the motor was worth fixing.
Sent from my iPhone using Tapatalk
-
He is not telling you to run the engine to operating temps, just merely that a proper compression test is done warm is all.
-
Will a warm motor give better or worse results?
Sent from my iPhone using Tapatalk
-
I believe that warm is better results as expansion of all parts means higher numbers. Cold is leaky.