Kenworth T800 rear engine mounts

[Andre_The_Giant]

Last weekend I changed the rear engine mounts on my 06 Kenworth T800 with an ISX engine. It took me about 4 hours from start to finish. I wanted to share my experience with others, and hope to help anyone attempting to do this.

None Common tools I used-
-30mm DEEP impact sockets ( 1/2" drive & 3/4" drive)(6 Point)
-30mm combination wrench
-1" & 3/4" impact gun
-Impact adapters, 3/4"-1/2" & 1"-3/4"
-Multiple sized impact extensions
-standard 20 ton bottle jack
-old brake drum and blocks of wood

I started by removing the bolts, you don't need to support the engine at all while removing them. It will not fall, even with the bolts completely out.. All of my impacting was done from below, with the combination wrench on top. I used the frame to hold the wrench up top, while paying close attention to the way it would spin (what it would hit).

The driver side was the most intimidating. There are a ton of wires/hoses along the frame rail that made it extremely tight. At one point i didn't think I could even fit a socket on. But you definitely can! I had to use a thin walled 1/2" drive 30mm, with an adapter to the 3/4"impact. The passenger side has more room, but was stuck worse for some reason. I had to use the 1" impact gun on it. After i removed the lock nuts, the bolts pushed right up and out for me (Luckily)!... I had a small Air hammer tool on standby and recommend you do too, in case they are sized in the old mounts.

Once the bolts were out, i placed the old brake drum, a couple pieces of wood, and bottle jack underneath.. I did not know where to jack it from. Jacking from the rear engine ears did not give me enough room to slip them out. What i found worked was jacking up from (what seemed like the most solid) rear part of the transmission. Pay VERY close attention to whats going to move upwards. I had to disconnect the drive shaft because it was close to hitting a cross member. Disconnecting the drive shaft was easy, just 4 bolts on the U-Joint caps and it pried right off. Be sure to support the shaft with a bungee cord, so it doesn't fall and hit the ground. I had to jack the transmission up quite a bit, i could hear my exhaust flex pipe bending (it made me cringe). But that's about it.

Once the old mounts slipped out the back, the new ones slipped right in. I lowered it down slowly and covered the new bolts with anti-seize. I couldn't find a torque spec anywhere, so i used the 3/4" impact to tighten. Hopefully i didn't over torque them :-/ But finally no more clunking! lol

Some things to worry about - you may have to cut or torch them out from what i hear.. If your bolts look extremely rusty, i would have a torch ready.
- Try to avoid removing the 4 bolts on the engine bell housing. I think it calls for red loc-tight and its only an aluminum housing. If they must be removed, heat the heads with the torch to loosen things up a bit.
-Also as mentioned the bolts may be stuck in the old mounts so you may have to air hammer them up and out.

Here's what mine looked like, hope this write up helps

         

[Andre_The_Giant]

Does anyone know the torque spec? I still can’t find any info on it, i would love to torque it

[Rawze]

(06-28-2019 )Andre_The_Giant Wrote:  Does anyone know the torque spec? I still can’t find any info on it, i would love to torque it

I was just about to point this out. - I would have been off the rails if that were my truck and no one used a torque wrench on every one of those bolts.

Those 10.9 LE bolts (look like they are roughly max 320 ft-lbs (assuming they are 20mm, they look like it in the pics). Would depend on the shank size. If they are the 20mm type, 275 with loc-tite would be acceptable. A phone call to the truck maker should answer it definitively though.

[dhirocz]

Nice to see that. I have a set of those on order for mine.

Mind if I ask what prompted you to change them? Wear and tear or were you having issues?

Careful with those u-joint strap bolts. The strap kits are cheap, and Spicer (I'm assuming you have an SPL250 u joint) says to replace them whenever they are removed. I had my driveshaft out once for balancing, and I instructed them to replace them...they cleaned them up and put the old ones back on. Driveshaft came loose in my driveway. Bolt heads came off. Talk about luck! I just drove it 50 miles home!

Needless to say, I was happy and pissed at the same time.

How does it feel now?

[Chamberpains]

And there is a torque spec for those u joint bolts. Just look up the manufacturer of the drive line. They give that info free online.

[Andre_The_Giant]

(06-29-2019 )dhirocz Wrote:  Nice to see that. I have a set of those on order for mine.

Mind if I ask what prompted you to change them? Wear and tear or were you having issues?

Careful with those u-joint strap bolts. The strap kits are cheap, and Spicer (I'm assuming you have an SPL250 u joint) says to replace them whenever they are removed. I had my driveshaft out once for balancing, and I instructed them to replace them...they cleaned them up and put the old ones back on. Driveshaft came loose in my driveway. Bolt heads came off. Talk about luck! I just drove it 50 miles home!

Needless to say, I was happy and pissed at the same time.

How does it feel now?

I changed them because of wear and tear, one was loose and the other cracked in half. Thank you for the axel info, going to order a strap kit now! Does anyone know a good place to find Kenworth torque and service information? I took the radiator out this Thursday and will be putting it back on Tuesday. I am worried about bolt torque, importantly the fan shroud because it’s fiberglass. If not does anyone know of a good bolt size torque guide?

[Nilao]

My international dealer never has an issue giving me torque specs for the parts I purchase there. Has given me part numbers as well if they don't have the part or its really expensive and it's a non-critical part like a surge tank. Some things I will only use OEM for.

[Andre_The_Giant]

(06-29-2019 )Nilao Wrote:  My international dealer never has an issue giving me torque specs for the parts I purchase there. Has given me part numbers as well if they don't have the part or its really expensive and it's a non-critical part like a surge tank. Some things I will only use OEM for.

Your very lucky, both dealers near me have the decent part prices. But have the typical Connecticut attitude. Whenever I ask for a torque spec the guys laugh at me

[Chamberpains]

Walk out to the service manager and ask them. Not that they'll be right. But they can point you in the right direction to find the info. Unlike the monkeys at the part department.