Piston Rings With Engine Still In?

[Dedaw]

Went and ordered the parts to do a re-ring today. Was wondering if anybody has done this with the engine still in the truck? Hoping I don't have to go borrow a picker and a stand.

[Keyav8r]

Only problem I see is keeping the grit and metal fines you get from honing the cylinders and ridge reaming off the crank. If you can make sure that the main bearing seats are clean before you install new inserts you should be okay. I assume you are replacing all the bearings while you have it that far down. Good time to replace the RMS, check/replace the crank pulley, check/replace the timing chain and sprockets and front crank seal also (if needed).

[Oyaji]

It can be done with other vehicles, so why not with the 4.0. As long as there is space to get the oil pan and the rod caps off (and back on again, properly torqued), may as well go for it - it would save a fair bit of effort.

 

I talked with the best machine shop around here yesterday - what I heard was encouraging: very rarely do they see 4.0 blocks coming in for boring, but they see a lot of 4.0 heads (many of them are cracked - they have a reputation for that around here). Though that is no substitute for proper measurement of the cylinder bores, it does say something for the robustness of the block. (Don't forget to mic the rod journals and rods while you have them off, too.)

 

The trick is to use plenty of protection/wadding to cover the exposed rod bearing journals on the crank and at the bottom of the cylinders bores to catch the grit and shavings released by honing, and to do a good job of washing down everything with plenty of solvent when done. I was horrified at the idea when I first heard of the method. I was ordered to use it on engines years ago by the shop owner for whom I worked; not one of the over one hundred that I saw go through the shop ever came back for warranty.

 

Provided that the rod bearings are still in the babbit, the main bearings can be reused. The logic is that since the rod bearings get their oil from the leftover flow from the mains, if the rod bearings are not worn down to the copper then the mains must still be fine.

 

This is definitely a shortcut and may offend the purists here, but such an overhaul is economical of money, effort, and time, and can add a lot of life to a tired engine. I suggest if you do go this route that it is a good idea to add a mechanical oil gauge before tearing the engine down to get a good idea of the condition of the bearings from the oil pressure, and to note trends in oil pressure for the life of the engine after your "economy overhaul" to help monitor the bearings for wear.

[Dedaw]

@Key- Going one cylinder at a time and putting rags over the crank tends to do the trick. :)

@Oya- Economy is key here. Want to at least get the truck running well and get rid of the blowby (rings are bad, already tested them, and tried other methods of clearing blowby first). Sad to see it sit for the last 2 months that I've been in school and too busy to fix her. If the mains are bad or something else major comes up, then it will likely be a full stroker build at that point.

 

Anybody recommend some free/cheap mods to do while I'm tearing her apart. Like to clear up some engine bay room. Only mod I've done as of yet is the valve cover mod cruiser wrote up.  :thumbsup:

 

Me and the little sis are tearing into her today. Awesome to share a little knowledge/jeep love with her!

[Keyav8r]

Just saw your reply. Put in a new oil pump while you have the pan off. At the least, put a rebuild kit in the existing pump.

[Oyaji]

Just saw your reply. Put in a new oil pump while you have the pan off. At the least, put a rebuild kit in the existing pump.

 

^^^ Good advice.

 

Also, if you have time and not money, some time spent lapping the pump body to the tight end of the tolerance for the gear-to-end-plate-gap can net phenomenal increase in oil pressure.

 

Just don't overdo it! Case in point - I overdid it on a VW Type 1 engine I rebuilt years back while still in my teens. I lapped the pump body flush with the gears, then skipped the paper gasket between body and cover to retain even tighter tolerance over stock, using only a thin smear of Permatex instead. When I went to prime the oil pump and filter with the starter, I thought my mechanical oil pressure gauge was faulty when it pegged at 250 psi... until I noticed the puddle of oil under the car. Turned out the pressure was so great it SPLIT THE OIL FILTER from top to bottom, and blew out a quarter or more of the crimp joining the filter body to the base, too! The pressure relief plunger in the engine case was insufficient to keep up with the pressure and flow from the "improved" pump. (I guess it is worth mentioning it was a fairly cold night for down here - about 35-40 degrees F - which sure didn't help, either.)

[nitroxsteve]

I have done this many times with diesel engines but never a gas burner. Biggest difference is the diesels have wet cylinder liners so no machine work is needed. I would wait before ordering any parts to see what you need first. Unless you know the complete history of the engine you could be surprised by over size pistons or bearings. I had to bore my 4.0 .060" when I did the overhaul at 150k miles. Also if the crank is in good shape you can replace the main bearings in frame too. You just remove the caps one at a time and turn the crank in the opposite direction of the bearing tab. You may need to put something into the oil hole to push against the bearing I used a bolt with the head ground down thinner than the bearing. Its alot of work to do it this way but if the cylinders are good and you don't have access to a hoist it will work.

[jeepsouth]

I have done this many times with diesel engines but never a gas burner. Biggest difference is the diesels have wet cylinder liners so no machine work is needed. I would wait before ordering any parts to see what you need first. Unless you know the complete history of the engine you could be surprised by over size pistons or bearings. I had to bore my 4.0 .060" when I did the overhaul at 150k miles. Also if the crank is in good shape you can replace the main bearings in frame too. You just remove the caps one at a time and turn the crank in the opposite direction of the bearing tab. You may need to put something into the oil hole to push against the bearing I used a bolt with the head ground down thinner than the bearing. Its alot of work to do it this way but if the cylinders are good and you don't have access to a hoist it will work.

I've done main bearings on a Toyota 22re this way too I used a roofing nail.

[Dedaw]

Life's been hectic, and been taking my time doing things RIGHT and in my typical OCD manner as I don't have to get this on the road right away. Anyways, I forgot that when me and my buddy did the oil pan gasket, the transmission was already out.  :rotf: So, I'm going to be dropping the axle to get it out, unless somebody has a better idea that I see in time.  :thumbsup:

[Dedaw]

Been at this for a good 2 hours now. Got the shocks disconnected and the sway bar unbolted, and that gained me about an inch.  :hmm:  What else??

[nitroxsteve]

Been at this for a good 2 hours now. Got the shocks disconnected and the sway bar unbolted, and that gained me about an inch.  :hmm:  What else??

it should drop considerably with the shocks and sway bar disconnected. You may need to unhook the track bar at the axle end.

[Dedaw]

 

Been at this for a good 2 hours now. Got the shocks disconnected and the sway bar unbolted, and that gained me about an inch.  :hmm:  What else??

it should drop considerably with the shocks and sway bar disconnected. You may need to unhook the track bar at the axle end.

I'll give that a shot. What about disconnecting the springs? Seems a little excessive, though.

[nitroxsteve]

if you have Jack stands under the frame and a Jack under the axle you should be able to lower the axle down far enough with the shocks, swaybar, and track bar UN hooked. do you have stock springs? if so it should drop far enough to remove the springs if yo wanted to.

[Dedaw]

Success!! Bottle jack between axle and frame rail did the trick