Dando Posted October 12, 2015 Share Posted October 12, 2015 So on my 90 mj with 4.0 aw4 I am having vibration problems that I am pretty sure are coming from the engine. It makes the vibration in neutral park drive reverse etc. so I doubt it's the driveline. I have replaced the motor mounts and trans mount. After changing those it's somewhat better but now it is pronounced between 1750-2500rpm then it goes away below and above that range. What can I start looking at? Need to figure this out its my daily driver Link to comment Share on other sites More sharing options...
HOrnbrod Posted October 12, 2015 Share Posted October 12, 2015 Check out the clearance between the exhaust pipe and cross member. Also checl the condition of the rubber exhaust hanger. Link to comment Share on other sites More sharing options...
Dando Posted October 12, 2015 Author Share Posted October 12, 2015 I thought that too, but when checked they seem fine and tight Link to comment Share on other sites More sharing options...
Dando Posted October 13, 2015 Author Share Posted October 13, 2015 Ok so I changed my fuel injectors last night for an extra set I had thinking maybe this would have an effect on the truck. Made no difference. I checked my fuel pressure and it is low, would that cause this issue? Link to comment Share on other sites More sharing options...
shelbyluvv Posted October 14, 2015 Share Posted October 14, 2015 Check the harmonic balancer. I had one spin and throw the engine off balance. Link to comment Share on other sites More sharing options...
Dando Posted November 7, 2015 Author Share Posted November 7, 2015 Ok so finally I tracked this issue down to the upper aw4 to 4.0 bolts being loose. I tightened them up this afternoon and took it for a test drive. Everything seemed right again the vibration was completely gone. After a few more blocks the vibration started to come back. When I got home the bolts were loose again and backed out a few threads. What can I do to stop this? Link to comment Share on other sites More sharing options...
gogmorgo Posted November 8, 2015 Share Posted November 8, 2015 Lock washers under the bolts? Make sure the other two bolts are tight as well. Also the torque converter to flexplate bolts. I had those bolts come loose, only I didn't catch it until it was too late. All but one had either come out completely or sheared off. The resulting engine-trans misalignment wrecked the flexplate and I'm pretty confident it also contributed to the main and thrust bearing problems that lead to me replacing the whole motor. You might also want to check your motor and trans mounts. Mine were bad, although that might be unrelated on a 300,000 mile truck. Link to comment Share on other sites More sharing options...
Dando Posted November 8, 2015 Author Share Posted November 8, 2015 Well I decided to try locktighting the bolts, we will see if that helps. Link to comment Share on other sites More sharing options...
Dando Posted November 8, 2015 Author Share Posted November 8, 2015 Took the truck for a test drive again after letting the locktight set for over 12hrs. Bolts loosened up again. Seriously what can I do? I'm not sure that a lock washer will work being the bolts are backing out of the block. Any ideas? Please help I need to fix this before work tomorrow Link to comment Share on other sites More sharing options...
gogmorgo Posted November 8, 2015 Share Posted November 8, 2015 If locktight didn't help, you're right, probably a lock washer won't either. If they're the original bolts, see if you can replace them with new. If they're not original, make sure they're the right bolts, and not too long and bottoming out in the block. If they are just backing themselves out, there's a vibration causing it. This may be one of the lesser symptoms of whatever is causing that, so it nay be pretty important to solve it beyond just putting the bolts back in. Again, are you motor mounts in good shape and the two larger bellhousing bolts still tight? Link to comment Share on other sites More sharing options...
HOrnbrod Posted November 8, 2015 Share Posted November 8, 2015 Sure does sound like the bolts are bottoming out. Pull one or more and stick an icepick or something in the hole until it bottoms them measure against the bolt. It may be as simple as a couple of washers on the bolt(s). Link to comment Share on other sites More sharing options...
Dando Posted November 8, 2015 Author Share Posted November 8, 2015 Motor mounts and trans mount are all new. Lower bolts are tight. Upper bolts have disappeared during the 4wd swap over a year ago now and currently I am replacing them with 3/8 - 16 x 1.75 bolts. Link to comment Share on other sites More sharing options...
gogmorgo Posted November 8, 2015 Share Posted November 8, 2015 That's the stock size, so far as I can tell. The mechanic who put mine back in used 2" long bolts, with a flat washer and a lock washer. I'm not 100% certain on the thread size, although they look like 3/8-16. There's a reasonable chance they were helicoiled, though, so I can't guarantee they weren't drilled deeper. But they held tight for ten months and 4,000 miles until I swapped my flexplate, and then a couple months and maybe another 1000 miles or so until I changed out my motor. How tight are you torquing them? One of mine was actually a bit distorted, looked like it got stretched a little. I'm pretty sure I put them back in to about spec. Link to comment Share on other sites More sharing options...
Dando Posted November 9, 2015 Author Share Posted November 9, 2015 It's hard for me to tell you how tight I am actually torqueing them down, i can't fit my torque wrench in the spot underneath where I am working. It's pretty tight though. I retorqued them this am now and we will see what happens today on my way to work, guess I'll try washers and lock washers tonight if it doesn't hold today. Link to comment Share on other sites More sharing options...
gogmorgo Posted November 11, 2015 Share Posted November 11, 2015 I used a few feet of extensions to get to mine when they were in the truck, but I also had the whole trans out, so likely the engine was tilted back for better access. I've also seen people recommend pulling the shifter and going through that hole, but I couldn't get that to work for me, my selection of extensions at the time either put me too long or too short. Link to comment Share on other sites More sharing options...
Dando Posted November 11, 2015 Author Share Posted November 11, 2015 I have been dropping the crossmember and lowering the engine/trans combo to get at the bolts using my longer extensions. Works pretty well. I can also get to the passenger side bolt with a wrench from the engine compartment. I used a new bottle of loctite Sunday and haven't had to try the lock washers yet as this seems to be working fine so far. Since Sunday night I've put on over 100miles and no problems yet, truck is a pleasure to drive again. Link to comment Share on other sites More sharing options...
gogmorgo Posted November 11, 2015 Share Posted November 11, 2015 Good to hear! Link to comment Share on other sites More sharing options...
Dando Posted November 17, 2015 Author Share Posted November 17, 2015 So I spoke to soon, this issue came back. Now I am fine as long as I only drive on city streets, but if I get on the highway the bolts loosen themselves again. I have tried loctite, lock washers, new bolts, and all three at once too. I can't get these bolts to stay in place. I'm guessing I have a vibration problem somewhere else that is causing these things to come loose. I can't find any other loose bolts. What can I look for? I really want to get this fixed before winter so my girlfriend can drive it on bad snow days. Any ideas? Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted November 17, 2015 Share Posted November 17, 2015 http://www.stage8.com/ Link to comment Share on other sites More sharing options...
HOrnbrod Posted November 17, 2015 Share Posted November 17, 2015 ^^^ You ever use these Adam? The three bolts on my exhaust header collector flange are constantly loosening up and taking out the gasket. Like Dando I've tried everything, and was going to try the Stage 8 bolts next. I'd need a set of 3/8" three fasteners, and as far as I've seen, they don't make a 3-bolt kit. Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted November 17, 2015 Share Posted November 17, 2015 Nope never used them , but I've heard great stuff about them . I'm sure they could Taylor make you a kit , after all they're just bolts . It's worth a try .. Link to comment Share on other sites More sharing options...
shelbyluvv Posted November 18, 2015 Share Posted November 18, 2015 I have used them on my buddy's J10 headers. Those figgin things would drop a bolt once a week. I put the Stage 8's in and have never lost or even had a bolt loosen up. Well worth the money! Link to comment Share on other sites More sharing options...
HOrnbrod Posted November 18, 2015 Share Posted November 18, 2015 Thanks Bo. But I'm not sure I understand how they work. My header collector to the exhaust flange uses three 3/8" x 1" bolts and nuts. I can see how they would keep the bolt from turning and loosening up out because of the clips on the bolt head, but what about the nut end of the bolt? What keeps the nuts from vibrating loose? :hmm: Link to comment Share on other sites More sharing options...
shelbyluvv Posted November 18, 2015 Share Posted November 18, 2015 The nut is a just like the head of the bolt. Think "flag bolt or flag nut" and you'll figure it out. Link to comment Share on other sites More sharing options...
HOrnbrod Posted November 18, 2015 Share Posted November 18, 2015 So the Stage 8 collector bolts come with nuts similar to the below? If so, I didn't know that. Link to comment Share on other sites More sharing options...
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