2.5 ff rebuild

**Merc 2.5** · 10-04-2018, 07:36 PM

Bobby thanks a ton. Since all mine r new but 2. I'll just order me 2 new ones and let bullet get yours. I know he bout need some to!

**TEXAS20225** · 10-04-2018, 09:20 PM

ive been in the same discussions before with fong, ive never ever had a stock rod bolt break in a single motor ive rebuilt ever!!!!!!!!! even in my own twisted up promaxs or 2+60 or 280 or 300 x ive had all of them my own ,the stock rods wont use the big head 260/280/300drag rod bolts ive never seen 5/16 head arp that are hi strength but that does not mean somebody does not make them. i closed shop last year i had seven blocks back from machine un built and all kinds of parts i just pulled the plug i was SICK dealing with some people .

**nitro_rat** · 10-04-2018, 09:31 PM

Originally Posted by TEXAS20225

ive been in the same discussions before with fong, ive never ever had a stock rod bolt break in a single motor ive rebuilt ever!!!!!!!!! even in my own twisted up promaxs or 2+60 or 280 or 300 x ive had all of them my own ,the stock rods wont use the big head 260/280/300drag rod bolts ive never seen 5/16 head arp that are hi strength but that does not mean somebody does not make them. i closed shop last year i had seven blocks back from machine un built and all kinds of parts i just pulled the plug i was SICK dealing with some people .

Yes, got my stock fishin' motor '79 175 partially disassembled. It broke a rod at 8,000 RPM's. This motor has been on the 'Stream since '81. Regular use by the original owner and then myself up to 72-7400 since then. Original owner scuffed a piston (#1) in the early 90's. He sent the original lower to Bob's at that time and had it coned. Cleaned the bore w/ acid and replaced the #1 piston. Some 15 years later I wound it to 8k for an extended period and the #1 rod almost cut the top of the block off. At first I thought the rod bolts had broken. After disassmbly it was clear that the bolts backed out. He didn't use loctite when he put it back together...

**Merc 2.5** · 10-05-2018, 05:47 AM

I'm putting all blame on the new hf torque wrench. It seem to b very accurate up to 25lbs but when set to 30 it wouldn't click. Moral of the story is. Stay away from harbor freight

**ChrisCarsonMarine** · 10-05-2018, 06:54 AM

I think I agree with you...and I'de be changing any other rod bolts you used that wrench on too,I've never broken a rod bolt while installing,thousands of them...Chris

**rock** · 10-05-2018, 07:48 AM

I have also never broken a rod bolt. I have felt several of them stretch as I was torqueing them. Pull them out and they have a distinct hour glass shape to them. Seen one back out cuz of blue Loctite and have seen a bunch of broken rods. Mercury uses a pretty good bolt. 35 lbs torque with red Loctite.

Rock

**Merc 2.5** · 10-05-2018, 06:23 PM

Originally Posted by Chris Carson's Marine

I think I agree with you...and I'de be changing any other rod bolts you used that wrench on too,I've never broken a rod bolt while installing,thousands of them...Chris

While I didnt get very far in ,the couple I did do in steps seemed to do "ok" would a dirty thread cause wrench to fail? Seems like damn wrench should had clicked at sum point? I should had been watching the bottom of the bolt I guezz but I never felt any difference on the wrench til it snapped. But again I can feel a bolt gonna break with a 3/8 ratchet, i was easing into the 30lb also. I didnt just (go to town) with it. Either way chris has me little nervous so I'm gonna replace the couple I did also, I've been very picky/precise so far that I wouldn't sleep good at nite thinking bout those rod bolts . I wanna get it on water b4 winter but ,if it takes a week longer so be it. So to the ones that's thinking about doing this for the 1st time. if something like this comes along , go the safe route. No need taking a chance!

**FORBESAUTO** · 10-05-2018, 06:32 PM

Dirty threads would have added drag and caused wrench to click before proper clamping force. The wrench calibration is just probably off. A torque to yeild bolt will only tighten so far then goes into an elastic state for “improved” clamping force (this is the point of the extra rotation after the last torque setting). Let’s say the bolts went into elastic state near 40 ft lbs and your wrench set at 30 was actually over the elastic state torque, it would never click but the bolt would just keep stretching until it gave up the ghost. This is more than likely what happened, wrench clicked just fine as long as you were below the elastic state of the bolted

**FORBESAUTO** · 10-05-2018, 06:35 PM

You can check the length of the bolts to a known good one, if they are the same length, you are ok. If any are longer, they have already been put into the elastic state and should be changed

**Merc 2.5** · 10-07-2018, 06:14 PM

I may not have need to but I went ahead and ordered 12 new bolts w/o torque to yield. Just standard torque method, not sure what kind they are,arp or sps or pro brand ordered from promarine , I'm 90% sure the bolts in it now r good but im just gonna go with all new standard type bolt, what's another 40$ for good insurance and not knowing 100% what state the others r in, I'm actually on a mini vacation in Gatlinburg tn at moment but hopefully by wed I'll have new bolts and start getting it ready for them .. question..... I think I should be able to chase/clean threads without taking pistons out? Nice clean rag under everything and just take my time ?

**dwilfong** · 10-08-2018, 08:16 PM

Originally Posted by Merclover

I may not have need to but I went ahead and ordered 12 new bolts w/o torque to yield. Just standard torque method, not sure what kind they are,arp or sps or pro brand ordered from promarine , I'm 90% sure the bolts in it now r good but im just gonna go with all new standard type bolt, what's another 40$ for good insurance and not knowing 100% what state the others r in, I'm actually on a mini vacation in Gatlinburg tn at moment but hopefully by wed I'll have new bolts and start getting it ready for them .. question..... I think I should be able to chase/clean threads without taking pistons out? Nice clean rag under everything and just take my time ?

I swapped my old bolts and bearings with out pulling the pistons no problem. Well worth the $40 for piece of mind.

**NeedOne** · 10-10-2018, 11:41 AM

Got a Q I'd like to add to your thread Merclover if you dont mind -
Whats up w removing the front half - can it be removed to inspect the crank and slapped right back together without issue or would bearings/ seals/ tolerances shift around... Any special procedures to note while doing that?

**Merc 2.5** · 10-10-2018, 11:46 AM

Not real sure what the question is be honest? Front half has to b removed to get to rods and crank. There is seals and o ring on top and bottom cap. Are you rebuild or swapping fronts?

**NeedOne** · 10-10-2018, 12:02 PM

Pulling front to inspect crank, and reassembling. Mainly wondering- is the crank/bearings and everything retained so it can go right back together without issue..