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Piston and Crank questions

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PATR8

PATR8

Jedi Knight
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Ok, I finally got the time to start rebuilding my engine, but seem to have run into an issue.

I have the crank installed, torqued to the repair manuals specification of 60-65 ft/lb. Installed the pistons and started to tighten them down to the crank. I tried to turn the crank just enough to get to the rest of the nuts by installing crank bolt and turning it. That is where the trouble started... I can not turn it even with a extension on it..

I know it should not be that difficult to turn it over. Where did I screw up?

One more question, with the connecting rod and the caps, should the indent on the caps and connecting rods that lock the bearings in be facing a certian direction, should the indents be on the same side, opposite sides?


As I was looking at the repair manual I noticed something else, each connecting rod has distinct sides to them, is there a direction they have to face?

I do not remember it being this hard the first time, probably because I did not pay this much attention to the details.


I am so darn tight on time I am basically able to do about 30 minutes of work a night on it in leiu of sleep.
 
PATR8 said:
I have the crank installed, torqued to the repair manuals specification of 60-65 ft/lb. Installed the pistons and started to tighten them down to the crank. I tried to turn the crank just enough to get to the rest of the nuts by installing crank bolt and turning it. That is where the trouble started... I can not turn it even with a extension on it..

Should it be that difficult to turn it over?
Click to expand...
In a word, "No."
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]if not, where did I screw up?[/QUOTE]
I can't tell you that without looking but, when that happens, it's time to disassemble and find the answer. Your motor won't work that way.
 
I believe that the main bearing caps and rod caps all are directional - have only one way they are to be bolted on. Otherwise you can indeed bind things up and can crack the caps if torqued down if they are incorrect. Not sure what car you are working on, but the big end of the rods to crank have a definite orientation in the TR6. Only one of two ways.

The prudent thing is to fasten one at a time and check the crank rotation for any binding. Turning the crank does get progressively "stiffer" but not bound up, especially when you start piston install. Should have cylinders and rings lubed up with motor oil.
 
almost all pistons will have a mark to put them towards the front and almost all rods must be connected to them in a certain orientation. you can get it backwards easily.

this sound like you installed the crank shaft and it turn ok, right? should have been able to turn it by hand.

i think it may be possible that you put a rod cap on backwards. see if the rod and cap have a number stamped on each or punch marks and make sure they are assembled on the same side.

reverse the order that you assembled it until you find what is binding? I've machined and built many many diesel engines in the past, engine theory applies to all engines so if you have any questions just PM me and I would be happy to help!!

it would help if you described what machine work was done to the block and your parts, and some more if you used a micrometer to measure your parts and clearances, if you don't have those tools Plastigage can be a good friend.
 
Install the crank first and spin to see if that part is correct, then put the rods and pistons on one at a time and keep checking. The rods and pistons are directional, and the caps need to be oriented the way they came out. Make sure you have the right sized bearings. It's possible you have oversized bearings against a standard sized journal. If you have any doubts, plastigauge and a micrometer will be very helpful checking tolerances.
 
simpson said:
I believe that the main bearing caps and rod caps all are directional -
Click to expand...

That is correct. Not only are they directional, each cap lives on a certain rod or main saddle. You can not mix and match unless machine work is involved.
 
if you took the main bearing caps off and they are not marked for location front to back and left and right and you mixed them up your going to have to have the block and crank send off and the caps machined and then line bored and honed back to original size. the rods and their caps are location and orientation specific too,

are they marked? did you mark them are you 100 percent they are all in the correct order and orientation, if so then you need to check bearing clearances with plasti gauge at a minimum, read too many stories about sending a crank off to be machined and either the bearings were wrong, the crank was not machined correctly and so the problems started, never take someones word they did it correctly you must measure and check! thats why I am paying someone to rebuld my engine that has experience with british cars and takes all the liability

Hondo
 
and PS when my crank was checked when it was pulled the main bearing journals were STD and the rod journals with 010 under sized, cant figure if that was original from the factory so need to check that too, maybe you have the same issue

Hondo
 
hondo402000 said:
and PS when my crank was checked when it was pulled the main bearing journals were STD and the rod journals with 010 under sized, cant figure if that was original from the factory
Click to expand...
Certainly not uncommon for an engine that has been serviced before; and the factory did sometimes have to service engines under warranty. I've even heard stories of American cars being delivered with one cylinder bored oversize, so IMO it is an absolute requirement to check everything, preferably several times.
 
Marking the main bearing caps and the connecting rods along with their respective caps can take various forms, from a series of dimples made with a punch to someones'poorly hand written numerals with an metal engraver.
If your TR8 was marked like the TR6's I've seen, it'll be the latter.
 
Patr8,
Can not swap cranshaft bearing caps in My Tr4a , or it binds...yes also happened to me the first engine rebuild, but caught it inmediately. And more important is to understand in which direction the so called thrust washers " White Metal" sits.
I envy your project. Good luck!
 
Not sure about the TR8, normaly the bearing shell has a small tang on one side and it engages in a matched slot machined in the rod and the rod cap.
If memory serves me well the tang for the cap is on the opposite side from the tang on the rod; you should verify this by checking the match marking on the side of the rod and it's matching cap. The tangs are there to stop the bearing shell from spinning in the rod.
 
No they are on the same side. One"fore" and the other "aft", though.
 
Well I had the caps on backwards, such a silly little thing that makes such a big difference.

I got the caps swapped around, the oil pick up cleaned up and put back on. Tomorrow I will try to finish up the bottom end and clean some more parts.

Thanks for the help, I am not sure how I missed it in the repair manual, picture included
 
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