How long have you had your replacement engine? What brand did you go with? Would you purchase another engine from them again? I have read a lot of forums on replacement engines and everyone seems to say ATK but they honestly seem like a bad company with horrible reviews , but I want to see if anyone has actually replaced there engine from ATK and has had any problems before I base it off of google reviews. What companies do you recommend? Titan has an engine for $1600 that has a 3 year unlimited mile warranty.

 

Not a replacement for an XJ but for a '96 Blazer. It's getting close to 50K miles on a Jasper engine. I've said it before and I'll say it again that it is VERY IMPORTANT that you know and trust the shop who is certified to install any brand of warranty covered replacement engine.

 

I got a rebuilt shortblock from Maabco in Tyler, TX and have 5000 on it and so far it's been perfect. I had a slight problem with one cylinder misfiring at idle because the rings in that cylinder took longer than the others to seat, but it's running perfect now. They suggested...no...demanded that I use a high zinc oil for break-in to condition the cam lobes, but after that use a good oil designed for high mileage engines. I had to supply my own lifters, oil pump, and pan and use a good assembly lube on the lifters. I knew nothing about this company and trusted my long time mechanic in choosing it, however he was confident in them. So far, so good. We inspected the engine before we put it in and all the bolts were torqued to spec, all the cylinders were .020 over, and all the rods and mains were .010 under.

 

yeah I’m thinking of going with them as well, just slap my new cylinder head on and go with new pushrods, rocker arms, and lifters. I just bought new lifters but I’ll probably buy new ones again since my engine is giving troubles. Why high mileage oil? Would a remanufactured engine be considered closer to “new”? Or is that just personal preference?

 

Newer engines for the most part use roller tappets so zinc compounds like ZDDP are not needed because there are less sliding forces requiring high lubrication on the cam. SO, newer engine oils don't have anywhere near the ZDDP in them, if any! High mileage oils have moderate levels of ZDDP in them to help lubricate engines that are slightly worn. The reason companies are eliminating ZDDP in their oils is zinc is good for lubrication, but the phosphorus part of the compound is bad for converters. Flat tappet lifters are under tremendous load in a sliding rather than rolling motion and require the best lubrication they can get. They can get away with using ZDDP in high mileage oils because they are usually used in older engines that need it. The EPA would like to eliminate the use of ZDDP totally.

Jeepers love Shell Rotella T6 Synthetic Diesel Oil because it contains over 1200 parts-per-million ZDDP. I use that in my XJ (5W-40) and it helps my oil pressure quite a bit. It's probably a little heavy to use in a new engine with tight clearances so I'm using Valvoline Maxlife High Mileage 10W-30 in my WJ and that has 600 ppm ZDDP in it. My mechanic put Penn-Life 5W-30 High Zinc oil in it for break-in. I know nothing about that oil. BTW, the converters on my WJ have 255K miles on them using Valvoline Maxlife for the last 160K miles and are still good. I've only had to replace one 02 sensor in all that time because the heater burned out.

Check the condition of the valves in that Clearwater head before you use it again, just on the chance that they got some damage. A bent intake valve will burn away quickly.