My 4.6 motor has a bad crank. Appears from oil starvation. The VIN is within the Death range for the 03's with dowel problems. My dilema is this. While the liners don't appear to have slipped yet, I am worried they might at some point, or the block might develop a crack if it hasn't already. No good way to test the block for cracks from what I can tell. Total cost to put a new crank in with new rings, head studs, cam, lifters, oil pump gears etc. is about $2500 as near as I can figure. Am I better off just to get a 99 or 00 4.0 motor and put it in? THey seem to be alot more reliable and much cheaper to purchase. In my area seems like a few for sale at salvage yards for 1500-1800. Is that a better option than rebuilding the stock block? My primary concern is dumping $2500 into the 03 motor and still having a crack in the block somewhere once its reassembled, or shortly down the road. What would you guys do in my position?

 

If your only concerned about fixing what is damaged now and you say it is your Crankshaft, then you can have your crank machined .10 under, install .10 over bearings on both rods and mains and bearings, replacement of the front cover to include the oil pump and all gaskets and seals for about $1200.00.

The problem with something out of a salvage yards is you have no idea of what you got. It could be in the same shape as what you have and be only a matter of time before it fails.

If money is no option then I would agree with you that Piston Rings, Cam/lifters, Valve Job/Heads re-surfaced would be in order.

The liner issue is always a possiblity and your only guarantee against this is going with a Top Hat Liner block like I did but this will cost you about $1800.00 just for the block.

I was in your same boat and dumped $4500 to rebuild my engine using a 4.6 Turner Top Hat Block with the only component that was not machined or new were the pistions.

It was expensive but I plan on keeping the Disco till its wheels fall off and when you look at like this, its a small price to pay.

 

Thats the thing I really don't want to dump that much into it to do the liners as well. Crank must be replaced, it is way too far gone to turn down. I hadn't even look at replacing the front cover. I was planning on just doing the pump gears for $100. Will not replacing the front cover be a potentail problem area?

 

Both your Oil pump gears and housing will suffer wear. The Gears are steel and the housing is Aluminum so you can write the script. I bought my cover from Turner Engineering in the UK for about half of what you would pay for the same part in the US. You'll have it in two days and save at least $300.00. You want the best pressure possible and the housing clearance plays a roll in obtaining the pressure needed.

If you weren't loosing coolant and haven't overheated it, I would go back in with your block, get a used crank and have it inspected and turned and polished if needed, replace bearings, Front Cover and Timing set, Cam and Lifters.

 

Thanks, definitely plenty to think about. I was looking at replacing rings too of course, but that isn't a bad list you have there to start with. Why the hell did rover make these trucks without an oil pressure gauge. Can't help but think a cheap gauge would have save thousands in ruined motors.

 

Maybe we should install a different oil pressure switch, the one in there is something like 7 PSI - when do you run around town with 9 pounds of oil pressure as "normal"? Maybe it was an old engineering math error - it was supposed to be 17 PSI as the low point alarm???

 

If you do go with a 4.0 there are a few things you need to do to make sure you do not destroy your tranny, I did this to mine and it was not fun. It is always a tough decision which way to go when the engine goes, at the end of the day a quality rebuild will be the best but then you have to consider the value of the vehicle, if you are keeping it for a long time then the investment is good. If you are going to sell it soon then it may not be worth it. Then with a lesser 4.0 block in you will not be able to sell it all that easy either under full disclosure and get what you want in price.

 

I have decided against this. I am going to rebuild it and cross my fingers there isn't a problem with the block. Going to use an aftermarket oil and water temp gauge for sure and hope for the best