Need a little advice from the expert mechanics

KevinP73 · 07-31-2016, 10:30 AM

My 2000 Dakota 4.7 has been having low oil pressure issues. I removed the motor and sent the crank out to be reconditioned. Everything looked ok as far as the bearings and the crank journals but I had the it turned 10/10 just to be sure. I used a local machinist who has done work for me in the past and has always done good work. I dropped the crank back in with new bearings and it rotated fine by hand. But as I was doing the rods it got progressively harder to rotate the assembly. I was concerned but really didn't know how tight I should expect it to be.
Now with motor back in the truck and everything is hooked up the motor isn't turning fast enough to start. It's definitely not a dead battery and the starter is new. I did notice the battery cables get VERY hot while I'm cranking it over. I'm going to double check my timing to make sure I'm not cranking against compression but I'm real confident that's not the problem.
What should I do next?

Any suggestions GREATLY appreciated.

Jrboulder · 07-31-2016, 10:36 AM

Did you measure the crank before you put it back in? Did you check all of the bearings for being the right size? Did you plastigauge anything?

DanielDudley · 07-31-2016, 11:20 AM

Did you accidentally mix up the rod caps ? That would do it.

Jrboulder · 07-31-2016, 11:20 AM

Quote:

Originally Posted by DanielDudley

Did you accidentally mix up the rod caps ? That would do it.

That would REALLY do it

Hugh R · 07-31-2016, 11:21 AM

or rod cap on backwards.

KevinP73 · 07-31-2016, 11:51 AM

I didn't plastigage the rods, only the crank. When I first noticed it getting tight checking the rod caps was the first thing that came to mind. I don't see how I could have mixed them up but it is a very slight possibility.
That being the case.... my only solution is to pull it all back apart and start measuring the rods to see if something got mixed. Would measuring the rods (assembled) reveal if this is the problem?

DanielDudley · 07-31-2016, 02:24 PM

It is also possible that the wrong bearings were sent to you. Start with the plastigauge. It will tell some kind of a story.

fastfredracing · 07-31-2016, 02:42 PM

You can get the pan off in a 4x dakota without pulling the motor, . Likely you have not damaged the crank just yet, if it has not rotated too many times.
However, reality is , that you will probably want this motor out, and on the stand to do any sort of crank /bearing work .
Either way, I would just loosen up rod bolts on individual cylinders till it freed up, then figure out what went wrong. Has to be wrong cap, cap on backwards, or wrong sized rod bearings . Doesn't a 4.7 have cracked rods ? If so, a mistake here should be pretty easy to figure out . I would not think that you could have missed that during assembly though.
Once you have figured out which one is tight, time to do a little measuring .
I hate all those motors, blech

KevinP73 · 07-31-2016, 03:30 PM

Quote:

Originally Posted by fastfredracing

You can get the pan off in a 4x dakota without pulling the motor, . Likely you have not damaged the crank just yet, if it has not rotated too many times.
However, reality is , that you will probably want this motor out, and on the stand to do any sort of crank /bearing work .
Either way, I would just loosen up rod bolts on individual cylinders till it freed up, then figure out what went wrong. Has to be wrong cap, cap on backwards, or wrong sized rod bearings . Doesn't a 4.7 have cracked rods ? If so, a mistake here should be pretty easy to figure out . I would not think that you could have missed that during assembly though.
Once you have figured out which one is tight, time to do a little measuring .
I hate all those motors, blech

It's not a 4x so it'll have to come back out. I'm not sure what you mean by "cracked rods". When I became concerned with things being too tight I checked that all the rod caps were on correctly (not backwards) so I'm confident that's not the issue. I also looked very closely to see if I could visually see a difference in the caps compared to the rod i.e. color, machine marks, casting lines. I couldn't see anything obviously different.

fastfredracing · 07-31-2016, 05:06 PM

I think they came in later 4.7 motors. Sorry.
Looks like there is no way around pulling it, getting the caps off, and seeing what size the journals are , and what size the big end of the rods are. Could plastiguage them one at a time as you remove them , to see if you have a few caps mixed, or there is something wrong with the whole lot . Bummer, there goes another weekend or two .

'

KevinP73 · 07-31-2016, 05:41 PM

What color plastigauge would be correct for checking the clearance ?

1990C4S · 07-31-2016, 05:51 PM

I suspect green plastigage. SPG-1

Clearance is about 0.0006" - 0.002"

I think you want to be around or under 0.001"

Someone else will confirm this...

fastfredracing · 07-31-2016, 06:00 PM

Green and red

KevinP73 · 07-31-2016, 06:22 PM

Thank you

KevinP73 · 08-08-2016, 07:38 PM

Thanks for the help everyone. Upon closer examination I discovered that I had mixed two rod caps. With everything re-measured (plastigauge green) oil clearance is now .001 on all the caps.
Now, another question before I screw something up. Do I need to replace the TTY hardware now that it has been torqued a couple times (once for the initial install, once to re-measure oil clearance) and then what will be a third time when I re-assemble again?

stomachmonkey · 08-08-2016, 07:50 PM

Quote:

Originally Posted by KevinP73

...Do I need to replace the TTY hardware now that it has been torqued a couple times ...

Yes.

Do you really want to go back in there?