Oyaji

Thanks for the responses. In the 2+ weeks it took to get answers here, I went to the best machine shop in my area and asked them the same question. They said that for every 50 to 100 4.0 heads they run through the shop, they only see about 1 engine block come through for boring. Along with the factoid that the blocks were high-nickel-content cast iron, this was encouraging information. On the downside is the guess that the Renix engines were more prone to overheating because of the (generally unfamiliar) closed cooling system and unknown operation and maintenance history of individual examples.

Use ASCII code, thus: ALT + 155 = ¢

Put on a "stinger" pipe 3+ feet long downstream from the header and you will be fine... unless the hot exhaust stream melts/burns something or you get pulled over for being too loud. Without the pipe downstream from the header, oxygen-bearing fresh air will be drawn up the header tubes between exhaust pulses and can rapidly erode the exhaust valves if the load is sufficient to get them really hot. Pressure in the upstream portion of the exhaust system does indeed drop "negative" (that is to say, below atmospheric) between pulses and can draw fresh air all the way to the valves if the tubes are too short. There is also this gem to consider: which you can balance against this: I concur. On start up, the ecu will ignore inputs from the O2 sensors and run off preset tables until the O2 warms up enough to provide accurate input. Then it goes into closed loop and measures fuel trims and air temperatures and whatnot. What's probably happening is the cold weather has caused the crack to increase in size and allow too much air in (too much air and the engine starts dumping fuel since it detects a lean condition) since the metal contracts. Over time, the hot exhaust gases cause the manifold to expand, sealing the crack up to a manageable level.

Mid-1950s Porsche 550 Spyder. Almost certainly a replica, because only 2 are known to still exist.

Not a good conditional measurement - it gets cold enough for Hell To Freeze Over for about half the year!

Last night my mother passed on, after a 15-year battle with Parkinson's Disease, and complete immobility and indescribable suffering since August. For the past 2 years when she was completely debilitated, she had care from myself and the rest of her immediate family, who took it upon ourselves to attend her in shifts around the clock. She breathed her last at home, surrounded by those who loved her. ... I hope you will allow me to wax philosophic, and to offer some advice which you must have heard and may have already have taken to heart: treasure your time on earth and the time you spend with family, and be good to all whom you encounter in life. The manner of passing may come either suddenly or with warning, but in any case the span of our days is finite. The only real choice we have is how we spend them, and I know I am not alone in trying to be good to those around me and in being unfailingly polite to all whom I encounter. And realize that you just may not be correctly reading people with whom you have friction, that they may be every bit as motivated as yourself in being good to one another, and that the fault of misunderstanding just might possibly exist within yourself, so make allowances and cultivate patience. By doing so not only will you help make the world a better place, but you also just might find it is already a better place than you thought.

^^^ 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.)

Y'know, having an axle with a manually-selectable center axle disconnect would provide a nice, safe, trouble-free 2-LO option, now, wouldn't it. As long as it wasn't used a great deal or for extended running, there wouldn't be much danger to the diff and spider gears, would there? (Thinking that having one axle disconnected would cause the diff to spin at double speed, potentially causing wear issues...) What do you guys think?

Also, whenever you are doing an electrical repair, it is a good idea to break out the soldering iron and shrink tubing instead of relying on crimped connections. It takes a wee bit longer, but the repair won't fail because of a corroded or loose connector later...

^^^ This - but you need to get the contact cleaner INSIDE the switch to clean the dash dimmer potentiometer. If contact cleaner doesn't do the job, then replace the headlight switch.

Ummm - what are you doing in 4-hi on dry pavement??? Use of 4x4 is plainly marked "part time", and is supposed to be used only in low-traction conditions. If there is no slip for the tires, geartrain binding builds up until something breaks...

^^^ THIS. . Because heat increases the resistance in wires and connections. Exactly. Could also be that the starter isn't grounding well when hot, for exactly the same reason mentioned above. If not that, the starter could be on its way out - it is turning more slowly than it should even when cold. If so, brushes might be all it needs; you should be able to tell once you pull it apart.

You seem fixed on the idea, so here are a few tips (you probably know them already, but it doesn't hurt to repeat them here, and to repeat them to yourself every time you take to the road laden): Towing is always more risky than just driving without a trailer, but any sort of driving has attendant risk. The more miles you drive, the greater the risk exposure. (I know, I know - how else are you going to get experience, right? But focus on safety and keeping speed low is never misplaced. My dad drummed that into us when I was a kid, impressing on my brothers and I that the family farm was at risk every time he sent us out driving ridiculously overloaded vehicles. But in our 4 combined driving lifetimes totaling 180+ years and an estimated 4 million+ miles, we have never had a crash.) Trailer brakes are great, but you still need to be able to stop safely if they fail. Car dollies aren't supposed to be used at speeds over 55 MPH (and for good reason: they tend to start "whipping" if you get faster than that, and can even exhibit this tendency at only 35 MPH). Any time you modify brakes, you need to do your own testing to ensure you have set up proper brake bias to avoid early rear axle lockup (an adjustable proportioning valve is required). Keep in mind that if you crash and there is an investigation of your vehicle, you just might be in for a world of pain - burden of proof will be on you to demonstrate that your tow combination was safe. (Even with the best and most diligent testing, you'll probably have a very difficult time convincing the court that your evidence is as compelling and valid as the factory letter of compliance with the federal brake standard - but you'd be completely screwed without it. You'd be best advised to go with the best OE factory standard tow package - and to not exceed its limits.) I'm sure there is much more to be said, but these thoughts come to mind right off the top of my head...

There was a well-used stock ex-military diesel tug for sale last year out in California (San Diego?) last year. If memory serves, the asking price was $4k - and the ad on CL stayed up for weeks and weeks.

Simple maxim: "It's easy to go, but hard to stop." Even stock 4-cylinder power is enough to get you going plenty fast enough to get into trouble. To reiterate what I mentioned before, emphasis should be on control and stopping ability before all else.

Anything is fixable given enough time, effort, and money. Sadly, there eventually comes a time when the harsh reality of simple economics kicks in and it just isn't worth it... even for the most devoted hardcore afficianado. :(

Since it runs, you won't have a spark issue... On a newly acquired vehicle, it's never a bad idea to start with a compression check to give you an idea of engine condition. If you have acceptable compression, this sounds like a fuel problem. Make sure you're getting full fuel pressure, and that it comes up quickly. If it doesn't, refurbishing/augmenting the high-current grounds might help... after the starter, the fuel pump and injectors draw the most current of all other electrical components, and less is available for them under the high demand of the starter. Combined with the current demand from the starter, drop in available power might delay full rise to full pressure. A vehicle that has high mileage and/or has sat idle for long periods may have marginal/partially clogged injectors. If you have full fuel pressure within a couple seconds after energizing the fuel pump, check the injectors for spray pattern and delivery volume. Injectors should not leak until energized, and once open should all have a uniform spray pattern, with fuel delivery within around 10% of each other. (Matched -flow injector sets are advertised as being as close in flow as within 1%.)

Again, if the starter is cranking the engine slowly, and if your battery is in good condition, your starter connection to ground could also be the problem. On problem starters for various engines over the years (including some big diesels in ag equipment that take 2 huge batteries to crank) I have run the battery ground to a mounting bolt of the starter, thereby offering the least resistance to the biggest power hog in the whole electrical system. Alternately you could check and possibly improve your ground connections: battery to ground, ground to engine, engine to starter. If that is no help, it's time to look at the condition of the starter. A better description of the symptoms would maybe net you better advice - you got us guessing too much because you gave few details. ;)

Maybe the new owner would sell it, if you could find out who he is. Maybe the last seller would help you with that - worth a call, I suppose. You must want a diesel parts truck pretty darn bad. :)

Pulling is not the problem - being able to maintain control and stop safely is. Being safe in normal traffic encountered on public roads should be the over-riding concern. I've gotten by on flat-land deserted country roads with too insubstantial a truck pulling too-heavy loads of farm equipment, and even then drove at extremely low speed (~25 mph average, maxing at 35 on miles-long straights). Even then, it was always a bad white-knuckled driving experience, only done because I had no alternative. Such is not ever to be recommended.

Is your compression good? As compression drops over the life of an engine, it will get progressively harder to start until finally it won't any more. If compression is good, have a look over your fuel pressure. If pressure is slow to come up or if you have voids in the line, it will take longer for fuel pressure to build sufficiently, thus limiting flow through the injectors and causing long cranking time. A marginal fuel pump or check valve could be the cause. As mentioned above, is the speed of the engine slow when cranking? Could be low supply voltage to the starter, or a starter on the way out. Low voltage to the starter will cause it to fail early - check your connections at battery and starter both.

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.

I saw it on this forum this year, but I don't remember in which subforum. For sure it is here somewhere though.

Can you check your tachometer against a known good one, like a tune-up tach? Such are more accurate than your dash instrument in any case, and since your dash tach is 20+ years old, it may not be as accurate as it once was...

In addition to the above, the MJ leaf packs are longer than the XJ's.