Blood of a Jeep Posted August 8, 2014 Share Posted August 8, 2014 Hey guys and gals. I'm new here, I've been lurking for awhile though. I have a problem, my Comanche has engine issues. She's a 90 with a 4.0 ax-15 2wd.the current engine has bottom end troubles. We're thinking it's wrist pin wallowing out the piston or rod knock or I don't know. I had a 94 h.o. lined up to go in but once I pulled it,I found the head was cracked in two places and the block is cracked twice as well. So now I'm pretty bummed. I'm curious though, if any one here sees any options that are ....inexpensive. Thanks. Link to comment Share on other sites More sharing options...
Eagle Posted August 8, 2014 Share Posted August 8, 2014 How many miles on the '90 engine? What's the oil pressure at idle and at highway speed? Link to comment Share on other sites More sharing options...
cruiser54 Posted August 8, 2014 Share Posted August 8, 2014 How many miles on the '90 engine? What's the oil pressure at idle and at highway speed? Yeah. What oil filter are you using? Link to comment Share on other sites More sharing options...
toid Posted August 8, 2014 Share Posted August 8, 2014 Ain't hijacking no threads here, but I HAVE to ask... What oil filter and bottom end knock have n common? I'm assuming lower oil pressure due to overly restrictive filter design not allowing "floating" on the bearings. Link to comment Share on other sites More sharing options...
Eagle Posted August 8, 2014 Share Posted August 8, 2014 Ain't hijacking no threads here, but I HAVE to ask... What oil filter and bottom end knock have n common? I'm assuming lower oil pressure due to overly restrictive filter design not allowing "floating" on the bearings. Fram filters are notorious for causing rod knock and low oil pressure in the 4.0L engine. Link to comment Share on other sites More sharing options...
oldseddie Posted August 8, 2014 Share Posted August 8, 2014 Too bad you're not in WNC. I have a block and crank to get shed of. Link to comment Share on other sites More sharing options...
Blood of a Jeep Posted August 9, 2014 Author Share Posted August 9, 2014 90 motor has 230000+/- oil pressure on the stock gauge reads low at idle and about mid-ways when revved up to 3000 rpm, which for some reason is my rev limiter. The oil filter is a microgard. Which iirc is a cheap Wix. But more on the motor, when it makes the noise the worst, it is rather deafening. It's loud. While it's doing this it misses and stumbles. If I rev without load it'll go out probably til red line. When under load it stops sometimes at 2500 sometimes at 3000, and by stop, I mean it just drops off like I killed it. Complete loss of power until my foot comes out of it. I'll try to get some videos of these phenomenons on YouTube but it could take a bit. And Olds, if I was anywhere near you I'd be on that. I've got a line on an unknown block and crank and rods and such with no head or accessories or oil pan from who knows what year in questionable condition for 200, but I think that's steep. Maybe I'm being cheap, I don't know. I just wish my Comanche ran as good as my 89 Wagonneer Xj. That girls got tons of go with no noises, and she was free! I paid 800 for the Comanche, the motor isn't the only problem either, it's electrical is wonky and the tranny needs a rebuild. All because I wanted one that bad. Link to comment Share on other sites More sharing options...
Eagle Posted August 9, 2014 Share Posted August 9, 2014 Sounds like a clogged catalytic converter. Does the engine make the noise when revved at idle? Usually such noises go away at higher RPM because the oil pressure is up. And the oil pressure gauge has numbers. "Low" is meaningless. What numbers are you reading? All too often people post that their idle oil pressure is "low," then when we point out that the factory spec for idle oil pressure is 13 psi it turns out their oil pressure isn't so bad after all. Link to comment Share on other sites More sharing options...
Blood of a Jeep Posted August 9, 2014 Author Share Posted August 9, 2014 Truck doesn't have a cat. With the engine at temp it looks to be below 20 so 13 sounds good. Oh and for the noise, it gets louder higher up. Link to comment Share on other sites More sharing options...
Blood of a Jeep Posted August 9, 2014 Author Share Posted August 9, 2014 To clarify, at idle it sounds great. No noise , sounds like a 4.0. As I accelerate the clack starts at 2000, steadily getting louder until its deafening. The oil pressure at idle is a smidge below the mark that I assume is 20. While under load it goes up to about 40. The truck has fine power until the magical 3000 rpm, at which time it looses all signs of life. It's completely stock with 30w oil a bit of MMO a little seafoam a jug of engine hunny and some oil stabilizer. Nothing added to or subtracted from the oil makes any difference. I've had the valve cover off , and all the rockers , pushrods and retainers look good. No wear or play. Engine is on time verified by 3 different people just to be sure. Grounds have been refreshed. Link to comment Share on other sites More sharing options...
Blood of a Jeep Posted August 9, 2014 Author Share Posted August 9, 2014 Link to comment Share on other sites More sharing options...
Tactical Bacon Posted August 10, 2014 Share Posted August 10, 2014 Starting about 4 years ago, Microguards went from being made by Purolator and being good filters to being made by Fram. So no, they're junk. Nowhere close to Wix. As far as running Seafoam in your crankcase, it's fine if you throw it in for 5 minutes of idling before you change the oil but driving around with it in there is asking, nay, begging for a spun bearing. Lucas Heavy Duty Oil Stabilizer is essentially a very heavy oil without any additives in it. Froths up very easily and can starve the engine of oil. All it does is mask a problem brought on by improper maintenance and/or general wear. Link to comment Share on other sites More sharing options...
Blood of a Jeep Posted August 10, 2014 Author Share Posted August 10, 2014 When I worked at a parts store a few months back ( almost a year) microgard was purchased by wix. From fram. All part numbers changed from being the same as fram to the same as wix, except the part numbers have mga or mgl I believe, before the number. As far as additives go , yeah I probably didn't help anything, but the noises were there when I bought it and refuse to leave no matter what's done. Link to comment Share on other sites More sharing options...
Tactical Bacon Posted August 10, 2014 Share Posted August 10, 2014 That's a change I hadn't heard about. Must have been in the last year. But good to know, I don't like to badmouth good products. Link to comment Share on other sites More sharing options...
cbreiter Posted August 13, 2014 Share Posted August 13, 2014 Could it be an exhaust leak? I've heard of some leaks by the manifold making strange noises. Link to comment Share on other sites More sharing options...
Blood of a Jeep Posted August 13, 2014 Author Share Posted August 13, 2014 I'm gonna say no on the exhaust leak. I do have one but this is different. Today though, I would say I "lost" a cylinder for awhike, then it came back. It probably did this three times. Very odd. But I had a thought, is it possible for an oil pump to still put out good pressure but low volume? The reason I ask is because the noise is quite loud upon first startup, but gets quiet once the oil starts flowing. It is also louder when the motor is up to temp. And lastly, it was low on oil today, maybe half a quart, topped it off and the noises were a smidge quieter. Link to comment Share on other sites More sharing options...
Eagle Posted August 13, 2014 Share Posted August 13, 2014 How many miles on the engine? If the noise is louder when the oil is hot (thinner), I would suspect a rod knock. It's a bit of a PITA but you can replace the bearings in situ by just dropping the pan. Link to comment Share on other sites More sharing options...
Blood of a Jeep Posted August 14, 2014 Author Share Posted August 14, 2014 That sounds like a viable option. Here's a short video. Its made with a phone so it's not a grade stuff, but you can here the knocking. Link to comment Share on other sites More sharing options...
Blood of a Jeep Posted September 23, 2014 Author Share Posted September 23, 2014 Reviving this to add a conclusion. The engine in the truck was torn down it had a majorly spun rod bearing one not so spun and 2 collapsed lifters. It has since been replaced with a 91 xj bottom end wouldve used the head but it was cracked between the first two valves. So it has a Renix head for now. On the lookout for a H.O. head. Link to comment Share on other sites More sharing options...
MuddFoot Posted September 24, 2014 Share Posted September 24, 2014 video doesn't work Link to comment Share on other sites More sharing options...
Blood of a Jeep Posted September 24, 2014 Author Share Posted September 24, 2014 Video is fixed. Link to comment Share on other sites More sharing options...
91Pioneer Posted September 24, 2014 Share Posted September 24, 2014 The problem is the Nissan keychain. Link to comment Share on other sites More sharing options...
Blood of a Jeep Posted September 24, 2014 Author Share Posted September 24, 2014 Naw not for me. My Z cars have done me better than my Jeep, in the reliability department, snow departments a different story. Thanks for the suggestion though. Link to comment Share on other sites More sharing options...
91Pioneer Posted September 24, 2014 Share Posted September 24, 2014 :thumbsup: Nissans will be more reliable than a Jeep any day of the week. Link to comment Share on other sites More sharing options...
mikejenn2 Posted September 24, 2014 Share Posted September 24, 2014 to me it sounds like valve train. I'm not the best person to tell u how to fix it but iv seen this b4. I don't know if u can just tighten up the lifters or if they need to be replaced. Link to comment Share on other sites More sharing options...
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