88 connecting rod bolts

jw1947 · Mar 29, 2020

I'm overhauling an 88 diesel, and have a couple questions related to the connecting rod fasteners:

First, what type of nuts should be used? Should they have any sort of locking mechanism? My engine had a mix of both marsden style self-locking and nylon locking nuts on the rod caps. Second, is there any value in trying to find replacement rod bolts? If so, it seems that direct replacements may not be available, but are there any substitutes that will work?

thanks!

oliver90owner · Mar 30, 2020

I?ve never come across big end bolts that are tightened to the yield point, so unless damaged, they should be re-usable on all but the most highly stressed engines (Formula 1, etc?). That said, we all(?) know that the rod bolts on early 310 engines were not up to the job!

Clearly someone has been in your engine previously and ?mixed and matched? parts. ?Nuff said?

Personally, I can't ever remember changing any rod bolts in the several dozen engines I have rebuilt but I have always changed nyloc nuts - and given them a dab of loctite for good measure. BTW get the right grade of nut for the job.

One question might be: Do you add on the torque necessary to run the nut down the bolt threads to the tightening torque specified for the bolt?🙂

RCP · Mar 30, 2020

I would not use the nylock nuts, they are not usually grade 8 equivalent and will not hold the torque required.

Rich

rustred · Mar 30, 2020

yes grade 8 nylock's are available, as the same with grade 5. use only grade 8 at work. plus the grade 8 will be a gold color and grade 5 silver if wondering. and yes we torque all nylocks on our units. use nylocks as its overhead equipment.

tom upton · Mar 31, 2020

https://www.agkits.com/waukesha-connecting-rod-bolts.aspx

RCP · Mar 31, 2020

I didn't realize that vendors were selling Nylock nuts for connecting rod nuts for Olivers.

Rich

tom upton · Mar 31, 2020

honestly I personally have not used any grade of nylock nut on a connecting rod bolt, but I guess some do?

88 connecting rod bolts

jw1947

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