markvtg

I just replaced the rod bearings on a 944 turbo and I am fairly certain I over torqued the rod bearing nuts. (Craftsman torque wrench!!!) I was able to rotate the crank by hand with the belt pulley when I was installing the rod bearings. However, when I went to start the car, all I had was a click....(yes the battery is fine). An odd thing, when I rotate, by hand, the engine by the belt pulley with the spark plugs removed, the engine rotates about 1/3 of a turn freely and then it becomes difficult to rotate. I lubed the connecting rod faces prior to assembly. What did I miss? I used Gylcol rod bearings, I was told this is what Porsche used. I really do not want to go back in but it appears I have no other choice. Any advice? Thanks in advance.

M758

did you replace the bearing for maintenance or because you spun one? I have seen cranks bend on due to spun bearings. A bend crank wont turn.

markvtg

I replaced the rod bearings for maintenance.

krystar

are you sure your valve timing is correct? u could be hitting a valve on piston face

carlege

you re hooked your starter or were down there some of the wires lost a true connection clean them off and re hook them. then see if the starter has enough power to turn. clicking usually means not enough power. i wouldnt jump to serious conclusions yet

jwlester

What about the fact that it won't turn freely with plugs out? Something has to be going on there. I'm watching closely because I will be doing this also when I dive into my pan gasket/suspension/whatever later in the year. Thanks.

Josh

2BWise

Sounds like you've got a rod cap on backwards.

Ask me how I know

StoogeMoe

That's what it sounds like to me.

markvtg

I do not believe my timing is off. I have the marking on the cam gear lined up and when I crawl under the car, I see the rectangle groove in the fly showing within the slot opening in the bell housing, all concurrent. Also, all the balance shaft marking line up. Am I missing something else?

I did clean the starter connections as one poster suggested however, this did not help and the when I turn the key to "start" the lights on the dash are still powered, so I do not believe this is battery related.

markvtg

I do not believe I have a bearing cap on backwards, each cap has a number stamped on one side, I made sure to only remove one at time to prevent mix ups and replaced the caps with the numbers on the cap side with the numbers on the rod side.

However this is not sounding good...another solid weekend under the car.

Mike C.

The vave springs will make the engine alternately easy then hard to turn my hand so that is not unusual. How much do you think you over-torqued the rod bearings? I'm skeptical that this would be a problem unless you really went far above the specified value (I would bet you would get into thread stripping issues before significant bearing deformation occurred). I would triple check the timing before going any further. You can use a flashlight to look into the cylinder w/plug removed to verify TDC.

peanut

if it won't turn by hand with the plugs out then you've got a serious problem there i would say. I'd drop the sump and check all the bearings carefully for any binding signs. I would say you've either got the wrong sized bearings or you've nipped a bearing up unevenly .
I take it you didn't remove and replace any other bearings ? did you replace the crank thrust bearings ?

I know its not much help now but I always check free turning before putting the engine back in.

Double check that you haven't got the timing off before you scrap a valve

Yarf

+1
Remove the #1 spark plug and insert a small diameter wooden dowel into the spark plug hole until it contacts the top of the piston. As the engine is rotated, the piston will force the dowel upward. When the end of the dowel is at its highest point, the engine is at TDC for the #1 cylinder. "
After you have set this all the timing marks should line up: both flywheel marks, both balance shaft marks and the mark on the Camshaft belt sprocket . Remember the crankshaft rotates twice for for one revolution of the cam shaft. Hope this helps.

Van

Did you change the main crank bearings? Could be a thrust bearing problem.

Over torquing a connecting rod bolt isn't likely to make it "tight" - it's likely to overstress the bolt which could lead to bolt failure, but it's not going to "squeeze" the cap on any more than the cap-to-rod mating surfaces allow.

Could also be something in the bell housing rubbing against the flywheel (did you lose anything in there?).

peanut

thats the method i use too but to be TDC the piston must be on the compression stroke of course or the timing will be 180 deg out.

I once had an engine that wouldn't turn . Turned out one of the lower bearings had shifted when i tighened up the rod cap and locked the con rod bearing up solid.