QL motor mounts - what's wrong?

[Grant]

The motor mount bolts on my 1250 keep loosening and falling out. I went so far as to replace the oil pan, get new bolts, and use lock washers but I looked the other day and sure enough only one bolt was left and it was half way unscrewed!! I'm not sure if there is a high temp. threadlocker, but is that the only/best solution? Anyone else have a similar problem? What's the remedy?

[BigMike]

Grant,the main thing I have found with QLs is all the cradle parts need to be in top notch conditon.Loose pan bolts are usually caused by bad ISO mounts.If everything is new and you are going to use thread locker I would put studs in the pan with locker and use nylon lock nuts and no lock washers.

[ksanders]

I'm with Mike. Something is usually wrong to cause them to keep coming out that quick. And I know its a pain to get those motors out by yourself too every time it happens. Are you using the original bolts or shorter ones that might not go as far into the pan and work out easier? Another thought is to VERY SLIGHTLY mess up the threads on the bolts so they don't go in or come out freely. It's an aluminum pan that it threads into so don't do this much or you'll strip the threads on the oil pan.

[Grant]

I put solid motor mounts on the 1250 last year so it's not that the ISO mounts are failing and 'pulling' the bolts out.

I hadn't thought of studding the pan and then using locking nuts. That might just work. Darn pain in the neck to do though.

[Jeff in Pa]

I put solid motor mounts on the 1250 last year so it's not that the ISO mounts are failing and 'pulling' the bolts out.

I hadn't thought of studding the pan and then using locking nuts. That might just work. Darn pain in the neck to do though.

Since I have narrow frames, I'm going to assume that you'll have similar clearance underneath with your 1250. Leave the engine in place and work from underneath.

Use studs that will leave about an 1/8" of thread showing when tightened with a flat washer and nylock nut. ( here's why ) Then get a jam nut ( thin ) and a regular nut and double nut the end of the stud. The thin nut goes towards the pan. Apply your favorite locktite to the oil pan end of the stud and tighten it up using the bottom nut. Then loosen the double nuts and replace with flat washer and nylock nut. Repeat three more times.

Jeff

[Grant]

Has anyone studded a QL that can tell me the size I need?

[Racenitro]

Unless you have new rubber mounts, they will not hold the two rails correctly and th ebolts will loosen up. Every Q/L I get I weld the cross brace between the two IOS rails. This makes a very sturdy cradle that will keep the pan bolts tight. I have jerry rigged new ruber mounts and the welded cradle and never have a problem.

Anything short of this is NOT going to last. Even IH made a replacement crossmember cradle so that you should tell you something. A 1250 should have the least vibration therfore if the bolts are loosening the problem is the two rails and the rubber mounts!

[Grant]

Unless you have new rubber mounts, they will not hold the two rails correctly and th ebolts will loosen up. Every Q/L I get I weld the cross brace between the two IOS rails. This makes a very sturdy cradle that will keep the pan bolts tight. I have jerry rigged new ruber mounts and the welded cradle and never have a problem.

Anything short of this is NOT going to last. Even IH made a replacement crossmember cradle so that you should tell you something. A 1250 should have the least vibration therfore if the bolts are loosening the problem is the two rails and the rubber mounts!

Except for the fact that I installed solid motor mounts last year (see my post above).

[BigMike]

Grant,I will take a leap that Frank meant regardless of the type of isolation(rubber or steel) that you may have issues without having the cradle upgraded.

[Racenitro]

BM
Thanks for having my back....You are correct...

Solid mounts may also contribute to the bolts loosening especially without the upgrade...becauce the two side rails may not be perfectly square/level with the pan.

[Grant]

I understand now.

I tried to get some threaded stud but they didn't have what I was looking for. Instead of running all over, I just got some 3/8 x 1 1/4" bolts with flat and heavy lock washers.

[Klapatta]

I have had very good luck using top lock nuts for high vibration applications.

37251_hr1c.jpg (16.61 KiB) Viewed 5484 times

They are commonly used on high quality replacement sway bar connector link applications which involves very much the same type of force.
I even use them on the hood pivot mount bolts as they never change once set.

[BigMike]

Those should be avilable in the Hillman hardware at your local big box or hardware store.

Ken,every time I have used that type of nut I have to run a tap through it to chase the threads clean