Piston Rings Worn Out, Time for a Rebuild

[rustystud]

Thanks. The break-in procedure he gave me says 2800r's, so we are going 300r past that. I found one member say he drove for 300 miles @ 2900rpm the entire time on the governor, and his engine is fine. Now if I see a poster say all the rods flew out the oil pan on their engine at 2700rpm for no reason, I'll be concerned. But, I have yet to find such story. 64hp is nearly 50% engine load, and max rpm. This is probably to keep the liners from glazing!

One of the reasons I believe the multifuel has the reputation for throwing rods is due to the rod bolts giving out. Now these bolts are on average over 35 years old and probably very tired. So taking the engine up to max RPM's is not a good idea for an old engine. Now if you have replaced all the rod bolts (especially with the new style) I don't believe this will be an issue. Since you went to such pains to do this rebuild right (I'm sure you had the rods checked out) I don't believe you will have any issues either.

 

[74M35A2]

Yes, rod bolt are new, less than one year old, and the later supposedly stronger style (12 point heads?). Rod bearings also new same time. Rods not further inspected/re-sized/x-rayed, as the engine did not have a prior lower end issue and never tried to compress liquid (stress).

 

[rustystud]

Yes, rod bolt are new, less than one year old, and the later supposedly stronger style (12 point heads?). Rod bearings also new same time. Rods not further inspected/re-sized/x-rayed, as the engine did not have a prior lower end issue and never tried to compress liquid (stress).

That's good that you went with the newer style rod bolts. I would have had the rods checked though. Just from normal use the ends can stretch and the beams can twist. Then the caps must be cut back and the hole resized, and the rods straightened. I always have my rods checked on any rebuild. Just cheap insurance. I normally don't line-bore the block unless there was a bearing failure or major over-heat issue.

 

[gimpyrobb]

I love getting my rod inspected, my prostate, not so much!

 

[gringeltaube]

... while rebuilding your engine?

 

[gimpyrobb]

Ill take it any way I can get it!

 

[74M35A2]

Well, for somebody that is a TM thumper, he says he is not going to follow the manual, and instead is going to modify it to his liking of stopping the steps at 2300rpm. I guess if it doesn't turn out right, I'll get to blame procedure not being followed. Stay tuned, he is waiting for the salt to clear off MI roads, so next update will likely be April timing.

 

[welldigger]

Well, for somebody that is a TM thumper, he says he is not going to follow the manual, and instead is going to modify it to his liking of stopping the steps at 2300rpm. I guess if it doesn't turn out right, I'll get to blame procedure not being followed. Stay tuned, he is waiting for the salt to clear off MI roads, so next update will likely be April timing.

2300? Now I know he didn't load the engine correctly. He needs to get on it after a fresh set of rings. Babying it isn't going to get him anywhere.

 

[74M35A2]

I know. He never even takes it to 2300rpm, but said he will for the break in, to get close to the 2800rpm. Ugh? He does lots of idle, lots of warm up before driving, etc.... He will stand on it for accelerating the empty truck, up to 1200F EGT, but there is black smoke rolling from the pipe when doing so, so it is over-fueled because he has the screw turned way up. A measured dyno pull will at least put a decent load on it to any desired value, but he really thinks the bottom is going to fly out if he follows the TM. He believes it will live much longer "if he is nice to it". Well, he's done 2 rebuilds so far on it in less than a year.... I hold my Sea-Doo engine wide open throttle for hours on end, and the most recent compression check showed about 10% above stock spec (a little carbon on top), after 19 years if using it that way since I rebuilt it.

I should not be beating him up. But after doing this a second time, I would follow the manual to a T.

Oh yeah. And he calls me a wuss? 2800rpm or back at you, silly rabbit.

 

[daytonatrbo]

I know. He never even takes it to 2300rpm, but said he will for the break in, to get close to the 2800rpm. Ugh? He does lots of idle, lots of warm up before driving, etc.... He will stand on it for accelerating the empty truck, up to 1200F EGT, but there is black smoke rolling from the pipe when doing so, so it is over-fueled because he has the screw turned way up. A measured dyno pull will at least put a decent load on it to any desired value, but he really thinks the bottom is going to fly out if he follows the TM. He believes it will live much longer "if he is nice to it". Well, he's done 2 rebuilds so far on it in less than a year.... I hold my Sea-Doo engine wide open throttle for hours on end, and the most recent compression check showed about 10% above stock spec (a little carbon on top), after 19 years if using it that way since I rebuilt it.

I should not be beating him up. But after doing this a second time, I would follow the manual to a T.

Oh yeah. And he calls me a wuss? 2800rpm or back at you, silly rabbit.

The final stage of any rebuild is to drive it like you stole it. Run it hard, just don't put it away wet.

 

[74M35A2]

I watched drag race engine builders on TV and in write ups, and they said "We build it up, fire it, set the timing, and then go ring its neck. No break in.". Fabulous!

 

[bluebones]

As someone with no experience with working on engines I learned a lot by reading this thread. So to everyone that has contributed, thank you.
One thing that was talked about frequency but at least to me never thoroughly explained was cylinder glazing. This link is the best explanation of cylinder glazing I could find. https://coxengineering.sharepoint.com/Pages/Boreglazing.aspx

 

[74M35A2]

It happens when you wuss out at 2300r's...

 

[gimpyrobb]

I know. He never even takes it to 2300rpm, but said he will for the break in, to get close to the 2800rpm. Ugh? He does lots of idle, lots of warm up before driving, etc.... He will stand on it for accelerating the empty truck, up to 1200F EGT, but there is black smoke rolling from the pipe when doing so, so it is over-fueled because he has the screw turned way up. A measured dyno pull will at least put a decent load on it to any desired value, but he really thinks the bottom is going to fly out if he follows the TM. He believes it will live much longer "if he is nice to it". Well, he's done 2 rebuilds so far on it in less than a year.... I hold my Sea-Doo engine wide open throttle for hours on end, and the most recent compression check showed about 10% above stock spec (a little carbon on top), after 19 years if using it that way since I rebuilt it.

I should not be beating him up. But after doing this a second time, I would follow the manual to a T.

Oh yeah. And he calls me a wuss? 2800rpm or back at you, silly rabbit.

Just tell him you'd like to take it for a spin around the block. While out of sight, FLOG IT.

 

[74M35A2]

I know, right? That's why he won't let anybody drive it.

 

[daytonatrbo]

Just peer pressure him into doing a few brake stands. (Or attempting anyway)


should make for a good "hold my beer and watch THIS" moment.

be sure to get it on film.

 

[rustystud]

The final stage of any rebuild is to drive it like you stole it. Run it hard, just don't put it away wet.

Yep that's what is needed. Our engines (and transmissions) at work are dyno tested to the max limits. We put a maximum load on it and take it to the highest RPM the engine is able to run at. We want it to break here not on the road. Plus you want to verify that the rebuild was done correctly.

 

[Aussie Bloke]

G'day everyone,....


Would'nt you run it in by finding a long hill to climb to load up the engine,....?



Aussie.

 

[74M35A2]

Yep that's what is needed. Our engines (and transmissions) at work are dyno tested to the max limits. We put a maximum load on it and take it to the highest RPM the engine is able to run at. We want it to break here not on the road. Plus you want to verify that the rebuild was done correctly.

Exactly. And that is a for-profit job with warranty.

 

[74M35A2]

G'day everyone,....


Would'nt you run it in by finding a long hill to climb to load up the engine,....?



Aussie.

Normally, yes, that or towing a loaded trailer is probably the best you can do. I have a precision chassis dyno used for emission system calibration that we can put his truck on and load to spec rpm and hp, so, lucky him, he can follow the manual, up to the point his feathers are sticking out anyway. It is has 4' diameter steel drum rollers sunk into the floor and can absorb up to 500whp and +200mph. The small twin roll "Mustang" type dynos are fabulously portable and low cost, but they are not EPA certified because they don't closely simulate a flat road via the twin rollers. Doesn't matter in this case, just info.