Tooling17039

Thank you very much for the information. Did you notice anything goofy prior to replacement of the mounts?

Understood. I just went through motor mounts on my 91 and am in the process of repairing the trans mount brace aswell as replacing the trans mount (weather and time are deciding that progress) That being said my 91s replacement motor mounts required some modifications to make them work. That was the main reason I asked if there was a preferred manufacturer. I'll start shopping around. Motor mounts were on the list for the 83 so I might as well check that off to rule them out.

Now that is very interesting. That is a great piece of advice. I can say visually they do have minor cracks noticeable. I will gladly order brand new motor and trans mounts. Does anyone have a manufacturer they prefer for the 300s?

I did indeed have the Vacuum advance disconnected and the vacuum line for it plugged when I set the timing. The idle currently hangs around 700ish. I never set it it's at the setting it was at when I got the truck. Great advice on checking for slop in the distributor aswell as coils mounting. I did put a new cap rotor plugs and wires on the truck right when I bought it. I've put about 1k miles on it I will check to see if there's any abnormal wear on anything. I'll save the duraspark 2 box for last, from what I hear they either work or they don't and I might be best to let that sleeping dog lie for the time being. I certainly won't rule it out but I'd like to confirm some of the other suggestions brought up first.

Good thought on the exhaust I'll check that tomorrow. The truck will only rumble in OD mainly at 55 but it is less noticeable up to about 60. I feel like the pedal input isn't as noticeable while it's rumbling. It's also an audio sound the truck doesn't shake. The only reason I'm dubious about the AOD is 55 to 60 is the speed it would have spent a lot of time with highway driving. It doesn't really feel like the trans is slipping but it's the only AOD I ever drove so I may not be picking up on a problem.

What you describe is about what I was seeing a 20 degree swing jumping randomly all around sounds about right. Negative on the ping it's a constant low pitch rumble when on the accelerator only around the 55 to 60 MPH range. It's really odd. It does it less loud when you just rest your foot on the pedal in that speed range also. It won't do it at a higher speed nor a lower speed in any gear. If I could record it I would. I originally thought it was a driveshaft or U-Joints I should have included that but the driveshaft is balanced and it's got brand new field lubricated U-Joints.

Like many guys in the hobby I work on the truck when I have time then I test drive the truck and the process starts over. Let me explain what I have going on and hopefully with a little help I can narrow down on a practical place to move forward. Theres quite a bit of unknowns with the truck I bought it with 160K miles and best I can tell everything is what it rolled out of the plant with. It's seen decent maintenance over the years but all the parts are going on 41 years old. Now on to what I am noticing. When I'm driving particularly in overdrive around 55mph it's got 3:55 gears so let's say around 1600 RPM I notice the truck has a very notice low pitch constant sound rumble. It's not super loud but it's definitely noticeable. I also feel like there's a reduction in pedal feedback when the truck is rumbling. I wouldn't say it falls on its face but it's not what I would expect. (I have a 91 with a 300 and while that's fuel injected I can't imagine they would be drastically different). I cannot duplicate this in another gear. Now on to additional observations or facts that may or may not be relevant. As someone who troubleshoots things for a living I recognize there's no such thing as too much information. When I got the truck the EGR was seized and the previous owner had the timing retarded to 3 degrees. (I checked it a few times, yes it was 3) it didn't appear the manifold was plugged when I inspected it while the EGR was off but I did not remove the manifold and verify. After I replaced the EGR and went to set the timing I noticed the timing mark dancing around on the flywheel. I believe I'm around 11 degrees advance which is what I found in my service manual. I'm wondering if the Distributor has slop in the bushings but would that manifest in this manner? I have verified the vacuum advance is operational. But I have to admit I have not verified the mechanical advance operation. Could that hanging up react in this manner. My 91 has an electronic distributor so I'm on a learning curve. Not surprisingly the truck ran much better with more timing but the AOD is still a question. It seems to shift like the descriptions I've read of an AOD. 1st to 2nd fairly crisp, it doesn't hold second long with light pedal input fairly crisp into 3rd in that scenario. If your in it it holds second longer and is softer into 3rd. Same goes for 3rd into 4th fairly noticeable shifting light or no pedal input and softer with more pedal. Downshifting it holds onto gears pretty long, especially 3rd but that sounds like a trait of the AOD. I've never owned an automatic vehicle let alone a 41 year old one so I don't know if I'm experiencing issues with the AOD or not. For many years I drove an 84 with a C6 and 460 that belonged to a place I used to work but I never experienced what I'm seeing here. The AOD is also a learning curve. I would also like to add the timing light I'm using I bought and used to set my 91s timing and it worked flawless with the timing mark being rock solid. Last thing I should mention is I've not done anything with the carb since I got the truck. The truck seems a little rich at idle but I'm not sure that it is under load or not. Carburetors are new to me and I'm not the kind of person who just randomly starts adjusting things without knowing what I'm doing. Could a fuel delivery issue react the way I'm seeing? This two is a learning curve. I like the learning curves but with so many I don't want to be hasty in a reaction. I'm a firm believer of you don't know what you don't know and it doesn't hurt to ask. Hopefully after your done you'll know exactly what's going on. Sorry for the mini novel but I would greatly appreciate any theorys or advice which avenue to pursue. Maybe I should be looking somewhere different all together thats a ll part of what pulls me into this. Learning is always a lot of fun. Right now I believe I need to lubricate and verify my mechanical advance. Maybe I need to start looking into a new distributor but I'd like some more feedback before I start down that path.

Do you think there's not much concern of the cracks migrating in the future? If the truck were to get another trans it would likely be a replacement M5OD like it had stock so this repair should be good. Would you think a washer around 1/4" thick would be an adequate thickness? I didn't measure the base metal but if asked to guess I would guess somewhere around 1/4". I do plan to remove this bracket to help to install a full all stainless exhaust including a high flow cat. It seemed logical to try and fit the two projects in with each other. So the bracket will be getting removed in the near future.

Great info. My initial thought was to go as soild as possible with the repair like you are saying. I agree there's rubber at all three points so I wouldn't see why the steel it's mounted to would need to flex. I'll try to give some back story You are correct if I were to guess I broke the mount about 2 years ago. I pulled another vehicle out of mud being a little harder on things than I would have liked. I used a chain and I assumed the sounds I was hearing were the chain moving under tension but one of the pops may have been this mount. It was when pulling hard with the truck like that (which I hadn't done to that extent in a long time) I was noticing my shifter moving a bit more than I felt it should which lead me to motor mounts last year. The truck sees intermittent use so last fall while I was under it checking other things I found the trans mount issue after double checking my work on the motor mounts. I periodically get under the truck I don't think I would have missed the broken mount since it was glaringly obvious last fall but you never know. Sorry if this got a little wordy. I'm thinking more solid is more gooder with the brace. I was fairly certain of that before I talked with my friend which threw me off a bit. I guess it leads me to wonder if older rigs needed more flex? I realize a 91 is older but I mean more 60s and 70s which he would have wrenched on quite a bit.

So while doing some inspections under my truck I found a rather impressive failure of my transmission brace. I'll also clarify I've already changed the two motor mounts which were indeed bad and likely caused this. I also have a brand new transmission mount to put in. I've not sourced a replacement brace so my original plan was to remove it, drill all the cracks I can find. Plug weld the drilled out parts. Then grind out and weld the rest. Grind all the welds smooth so the new trans mount rubber sits as it should. On the bottom fully weld in a piece of 3/8 plate I have one hand using stich welds so I don't turn the thing into a pretzel. Anyhow I mentioned how I intended to repair this to a friend of mine and he strongly felt I needed to drill the cracks and only plug weld the holes, leaving the rest go. Then add the plate as I planned but not fully welding it only doing 1" stitches with say a 1" gap between. He was pretty sure the brace itself needs to flex or it will fail again. I thought this was a neat discussion topic so I thought I'd drag it over here. He has far more experience doing fabrication than I do and I plan to follow his advise. All the same I was curious if anyone else had to do any repairs like this and what their thoughts or experiences were. It's one of those things where I see it could have a few schools of thought to apply which might make an interesting discussion.

If there's interest I can post stuff on my 91 in a different thread. I bought the truck when it was 8 years old and I was 15. You never really can get over your first love. I'm so glad I kept it all these years. The exterior is starting to get rough but I'm more focused on what makes it go before doing any body work to it. Next up for it is an all stainless exhaust and high flow cat. I am really curious to see if there's a noticeable change in it. If I'm impressed with the results I may do the same to the 83 at some point.

I've been on the fence about buying a smoke rig. I think I'll try and replace all the old lines I can lay my fingers on and go from there. If I still have leaks, smoke sounds like the logical way to go about finding the leaks. I'll probably try and hit it this weekend. I'll have to dig back in the archives for posts coming up. I'll be doing some work to my 91 which is the wrong Era for this site. I have a bunch of older work I can put on here though so stay tuned. I think the next post I'll go over how I fixed the old rear bezel mounting brackets that basically all shattered when i took it apart to fix the missing letter on the tailgate.

Thank you, I'll look into this. If I don't have to take the entire dash apart to address the leak, I'd take that as a win. I'm not sure when I'll get to it but I'll try to remember to take some photos when I do.

I am using the exact same Labeler with shrink tubing. I went black on yellow. I really like that labeler. We use Brady at work where I'm an industrial electrician but to be honest Brady costs quite a bit more. The work flow is better with Brady but most of us in our home shop value functions at a lower cost so the Brother being a little slower doesn't really matter. I ran out of labels so I still have some to finish up on the 83. If you spot a few missing labels, they be added soon.

I can hear it ever so slightly when I open the glove box. I'm hoping a control devices plastic hasn't cracked and it's just a line. And why not here's a photo I took during my test drive tonight. The truck ran pretty good I still feel like there's room for improvement but that's just how I am. My 91 is like a whole new truck after I went through everything on it so I'm hoping to get the same results with the 83. I'll get into the story more as I post more on what all I've done so far on the 83 the guy that had it before me didn't have it long but he definitely left his mark. I've undone most of those things. And even though it's a brick nose and a 300 here's a photo of where my 91 is at now. I took this right before I buttoned up the cooling system and fired it up. So over time I'm hoping to get the 83 in similar condition. It all takes time and patience.