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Old 06-16-2010, 10:17 AM
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Rod main caps on backwards... what now?

Well I'm ashamed to admit I had my head up my ***** and installed the rod caps on backwards. (tangs on opposite sides). Motor ran less than 4-5 minutes at a time. Maybe a total run time of 30mins, never over 1500rpm and no load (car on stands in neutral). Pulled all teh caps to check them out and I see no black or signs of heat. There are some small scuff markings but nothing I'd say is damaged. No grooves etc…

The reason I pulled the pan is the motor would start up and run great for 2 minutes or so, then it would start progressively ticking louder and louder. Oil pressure was rock solid middle of the gauge (factory gauge no numbers). Then the engine would start to loose rpm and stall out. Almost like a hydro lock. (did immediate comp test at this point 125 across the board).

So I've narrowed it down to 2 options.

Slap the caps back on the right way and run the bastard

Or order a new bearing set and replace the bottom bearing inserts and run the bastard.

What are you guys opinions?

Lastly this is a 4 cyl 2.0 4g63T motor. ( I know it’s no SBC, lord I wish it was! ) But I figure the same general rules apply.

Thank you!

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Old 06-16-2010, 11:46 AM
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Toss out ALL of the bearings including the top half in the block. A cotter key flattened in a crank oil hole (and turning the crank) will take the top bearings out. You don't know if they're damaged until you see them and once you see them, toss them "just to be sure". Without mic-ing them, there's no way to tell if one of more have been compressed on the ends. If there's no real damage (you're the judge here, we can't see it. Seizing didn't happen with NO damage) then toss in a new set and run it. It'll either work or it won't, but if it doesn't (knocks, seizes, etc) at least you know why, now. If not, enjoy it and the lesson you learned.
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Old 06-16-2010, 12:58 PM
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Forget about the bearing condition--they are junk, what about crank.
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Old 06-16-2010, 01:03 PM
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Quote:
Originally Posted by ForceFed86
Well I'm ashamed to admit I had my head up my ***** and installed the rod caps on backwards. (tangs on opposite sides). Motor ran less than 4-5 minutes at a time. Maybe a total run time of 30mins, never over 1500rpm and no load (car on stands in neutral). Pulled all teh caps to check them out and I see no black or signs of heat. There are some small scuff markings but nothing I'd say is damaged. No grooves etc?

The reason I pulled the pan is the motor would start up and run great for 2 minutes or so, then it would start progressively ticking louder and louder. Oil pressure was rock solid middle of the gauge (factory gauge no numbers). Then the engine would start to loose rpm and stall out. Almost like a hydro lock. (did immediate comp test at this point 125 across the board).

So I've narrowed it down to 2 options.

Slap the caps back on the right way and run the bastard

Or order a new bearing set and replace the bottom bearing inserts and run the bastard.

What are you guys opinions?

Lastly this is a 4 cyl 2.0 4g63T motor. ( I know it?s no SBC, lord I wish it was! ) But I figure the same general rules apply.

Thank you!
You'll need to tear it apart. It's likely that the reversed caps resulted in an offset edge forming where the upper and lower bearing shells meet. This will have wiped out the hydrodynamic oil wedge that circulates between the bearing and journal resulting in damage to both bearing and journal surfaces. This is especially likely on the thrust main.

Bogie
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Old 06-16-2010, 01:04 PM
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As I said earlier I don't think the bearing had anything to do with the motor "seizing". To stop an engine in motion would take alot of heat and friction. There were no signs of heat in any of the bearings. Good idea on the rod bearings though.

I did not install the crank bearings backwards, just the lower rods caps.
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Old 06-16-2010, 09:57 PM
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Quote:
Originally Posted by ForceFed86
Well I'm ashamed to admit I had my head up my ***** and installed the rod caps on backwards. (tangs on opposite sides). Motor ran less than 4-5 minutes at a time. Maybe a total run time of 30mins, never over 1500rpm and no load (car on stands in neutral). Pulled all teh caps to check them out and I see no black or signs of heat. There are some small scuff markings but nothing I'd say is damaged. No grooves etc…

The reason I pulled the pan is the motor would start up and run great for 2 minutes or so, then it would start progressively ticking louder and louder. Oil pressure was rock solid middle of the gauge (factory gauge no numbers). Then the engine would start to loose rpm and stall out. Almost like a hydro lock. (did immediate comp test at this point 125 across the board).

So I've narrowed it down to 2 options.

Slap the caps back on the right way and run the bastard

Or order a new bearing set and replace the bottom bearing inserts and run the bastard.

What are you guys opinions?

Lastly this is a 4 cyl 2.0 4g63T motor. ( I know it’s no SBC, lord I wish it was! ) But I figure the same general rules apply.

Thank you!

Awesome somone from wichita, ks sorry for your bad luck. I would personaly go ahead and put new bearings in it.
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Old 06-16-2010, 10:10 PM
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Quote:
Originally Posted by bracketracer
Awesome somone from wichita, ks sorry for your bad luck. I would personaly go ahead and put new bearings in it.

Nice to meet you, U out at the track much?


Anyway....

Digital camera makes them look worse than they really are... I didn't think they looked bad until I saw the photos. Maybe I'm getting blind in my old age...


These two were the worst. Upper bearings looked better than the lowers.

You can see a slightly dark indented spot, I'm guessing this was most of the resistance starting to clearance itself.







You can see the outer edge is starting to wear a bit on this one...




Random rod journal...

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Old 06-17-2010, 04:31 AM
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The blessing was that you didn't run the engine under any load.

I'd trash the rod bearings (all of them) and as long as the crank hasn't grooved- and I'd be amazed if it was damaged, the soft bearing material is what takes the brunt of it- replace the rod bearings w/the caps properly orientated.

If you are a worrying type, remove the crank, take it in for assessment at the shop, remove the rods and have them checked and resized if needed.

Personally, I'd replace the rod bearings and run it.
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Old 06-17-2010, 06:46 AM
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Already ordered a new set of rod bearings should be here tomorrow. I was thinking while I was in there would it be a good idea to change out the crank bearings just for the hell of it? I figure there was some metal in the pan. Any reason not to?


Don't think I'll run the boost as high as I was with this engine. Probably put it back to stock and just drive it. Previous oem motor went 11.92 @ 116. It was a blast. Stayed together roughly a year before a rod went.

Thanks guys!
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Old 06-17-2010, 04:35 PM
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Quote:
Originally Posted by ForceFed86
As I said earlier I don't think the bearing had anything to do with the motor "seizing". To stop an engine in motion would take alot of heat and friction. There were no signs of heat in any of the bearings. Good idea on the rod bearings though.

I did not install the crank bearings backwards, just the lower rods caps.
OK getting back to this, I saw further down you got it apart. What happened to seize the engine is that with the rod caps reversed the bearings in the caps were jammed into the radius where the rod journal fairs into the cheek. If there is any serious crank damage it would be in this area. The seizure was simply a case where the engine as it warmed up and parts expanded, the bearing pressed against the journal radius gradually ran out of clearance and clamped itself to the shaft. Except for crud that was probably pulled off the bearing and circulated making grooves in otherwise smooth surfaces, I doubt any serious damage was done, unless you see discoloration along the edge of the rod caps from frictional heat. I'd guess the bearings will need replacement.

Bogie
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Old 06-17-2010, 08:03 PM
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Yes i run at the track alot. 1955 chevy 2dr wagon blue and white runs 12,s im sure youve seen me out there. Do you go there much?
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Old 06-17-2010, 10:23 PM
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Quote:
Originally Posted by oldbogie
OK getting back to this, I saw further down you got it apart. What happened to seize the engine is that with the rod caps reversed the bearings in the caps were jammed into the radius where the rod journal fairs into the cheek. If there is any serious crank damage it would be in this area. The seizure was simply a case where the engine as it warmed up and parts expanded, the bearing pressed against the journal radius gradually ran out of clearance and clamped itself to the shaft. Except for crud that was probably pulled off the bearing and circulated making grooves in otherwise smooth surfaces, I doubt any serious damage was done, unless you see discoloration along the edge of the rod caps from frictional heat. I'd guess the bearings will need replacement.

Bogie
Thanks for the input! I noticed no discoloration. Would you suggest replacing the main bearings as well? I had planned on putting it back together this weekend w/ new rod bearings only. I'll keep the thread updated.



Quote:
Originally Posted by bracketracer
Yes i run at the track alot. 1955 chevy 2dr wagon blue and white runs 12,s im sure youve seen me out there. Do you go there much?

Yup I've seen the car for sure. I'm in the flat black rx-7 with the grand national motor. 10.60's is the best I've gotten out of her so far.


Last edited by ForceFed86; 06-18-2010 at 06:44 AM.
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Old 06-19-2010, 01:01 PM
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Fired her up this morning... same thing happens.

I thought for sure that was it. The motor sure turned over alot easier with the caps on correctly. Fired it up and after about 5 mins The clacking noise came back and the engine slowed itself to a halt. I must have measured incorrectly with the bearings or already egged the caps? Although if this was happenign wouldn't it show on the bearings? Not sure but something isn't kosher. Motor won't turn over by hand after it stops. After it cools off it turns over just fine.

I could just mat the pedal to 7k when it's cold and let it clearance itself?

Probably just take it back out and do it right this time around instead of trying to save a few bucks.

Thanks for the help all!

Last edited by ForceFed86; 06-19-2010 at 03:19 PM.
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