DrShaggford

I've got a 98 with an unknown year motor in it that has started acting up. I'm debating on either swapping the motor with one from the JY or maybe doing a basic rebuild on it.

What are some things to look for when deciding if it's even going to be salvageable?

Would it be worth doing rebuild with just doing rod bearings, main bearings, pistons, rings, lifters and pushrods? I'm pretty sure it needs a new head regardless.

What kind of machining would HAVE to be done? I assume it will have to be bored or at the very least honed. Can I get away without decking the block or head as long as I check for straightness?

If I do over-bore it, how far over can I go before I need to start changing things like injectors and fuel pressure regulators?

Are there any specialty tools I would need aside from the obvious hoist and stand?

Also I've never been deeper than a head in a large motor (I've rebuilt 2-strokes) and from the bottom side I've never done more than replace an oil pump. Am I getting in over my head?

Thanks in advance. You guys always have great advice and bring up things I would never have thought of.

brielly1

Do you have a high quality and trustworthy machine shop to go to? That to me would be the most important aspect when considering a rebuild. If so, you would need to disassemble the engine and then let the shop determine what work needs to be done. There's no need to go crazy overboring the engine as it will add little power. Obviously if you rebuild it right you'll have a great engine for a long time but it will most likely cost more than just swapping in a used motor. I guess it depends on how much you want to spend but the rebuild itself can certainly be done with minimal tools. There are also a few decent videos available to guide you through the process.

Cummins93

1: Can you define "acting up"?
2: Time is money, and money is money. How much is your time worth plus your machinists time worth compared to buying a stroker long block?
3: Leak down test on current motor please.

DrShaggford

brielly1, The town over from me has quite a few machine shops. I would definitely need to go in and talk to a few to find one I like but I don't think it will be problematic. Also, thanks for the tip on looking at some videos. I'm not sure how I didn't think of that.

DrShaggford

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Fred/N0AZZ

This is "NOT A FIRST TIME PROJECT" if you plan on it running for long or at all, have an engine machine shop build it for you.

madmanmarty

I agree ^^^^.

Radi

That could affect the cam bearings which aren't the simplest things to replace.

There is basically no accurate way to know what machine work you'll need to do until you open it up.

tech

I found this web site maybe somebody knows how they are ? http://www.hesco.us/products/7544/hi...5#.W_hvdOhKjIU

awg

If wrecked XJ are common near you, a used motor may be significantly cheaper, being they are quite long-lived

Having said that, my mate has O/H many XJ motors, just hones the block, and replace all parts from Rock Auto etc.
Head work however is practically inevitable once apart with an old motor = $, cam bearings, mavbe crank turned etc etc

dave1123

If you do decide to get it rebuilt by a shop, the cleaner you get the parts, the less it will cost in labor. No machinist wants to spend time cleaning up the parts to get measurements before he starts working on them. The head will have to have the valve seats and faces ground, new springs and stem seals, possibly a surface milling cut to straighten it, and a hot tank boil to clean the water jacket. The block should be boiled and new cam bearings installed plus all new core plugs. You may not need new pistons if the cylinder fit is within tolerances and it only has to be honed. On a straight block engine, you don't get much out-of-round wear like you get in a V engine. It also depends on if you're expecting another 2 or 300K miles out of it. If so, you should bore it and replace the pistons.

The key to a good rebuild is attention to detail. If you don't hit all the tolerances right, they will come back to bite you. Something as simple as the distributor shaft, bearings, and gear can cause problems down the road. What I've done in the past is install a used motor, then take my time rebuilding the original one at my leisure. That way I have a fresh bullet to install when the used one dies. I could do this when I was young and single with not many commitments other than my job.