Rod caps on backwards... Damage anything?

[forcefed86]

Just put a motor together upon first start up the motor ran great until it warmed up then it started progressively tapping louder and louder until it stalled out. It's like the motor is being dragged down with load to the point of shutting off, not an immediate stoppage.

Thought this was due to oil loss, but my oil pressure seems to be fine. Pulled the pan and all bearings all look good. I did however have the damn rod caps on backwards. Could this have cause the tapping noise? Any damage to look for? Other ideas on why the engine is Tapping loudly once warm? The motor has only idled up to 1500rpm never had any load on it etc. maybe run a total of 30 minuted on and off. Never more than 5 mins at a time.

Thanks

 

[LiquidX]

Pull the caps and look at the surface on the cams, cam caps and the cam rests on the head. The cam caps are machined for their location and orientation for that specific head. It's very possible that one or more things are damaged/scored.

 

[1995gsx20g]

+1 alum does not take any abuse.

 

[forcefed86]

I did this before taking off the oil pan and checking the main and rod caps. All is good. Up top. It's almost like the oil pump is hydro locking. Not sure what is causing it....

 

[SrKegler]

He's talking about rod caps, not cam caps.

Yes you can damage something. Your motor getting dragged down was the bearings siezing on the crank. Pull the rod caps off and check. .

 

[LiquidX]

He's talking about rod caps, not cam caps.
.

>.<

Thanks for catching that for me. I really must have read that wrong.

But yes, even rod caps on backwards are bad as well but at least you have soft bearings taking the abuse.

After you put everything together the first time did you make sure the crank would rotate by hand and not bind up?

 

[forcefed86]

He's talking about rod caps, not cam caps.

Yes you can damage something. Your motor getting dragged down was the bearings siezing on the crank. Pull the rod caps off and check. .

This is what I did, bearing surfaces and crank look good. If the bearings were seizing on the crank there would be black wear markings. No Sign of an ytype of heat and or wear.

I have not reinstalled the main/rod caps, was thinking about ordering another bearing set and replacing the bottom bearings? Think this is overkill?

 

[LiquidX]

You checked all of them?

Be sure to lube them up very well when you re install them though.


You eliminated your BS correct?

 

[forcefed86]

You checked all of them?

Be sure to lube them up very well when you re install them though.


You eliminated your BS correct?

\

Yes, and yes.

 

[diambo4life]

Like said, the caps are actually cast as one piece and cut in 1/2 to ensure complete roundness. The reason why they are location and orientation specific. Once you install them backwards, you destroy this tolerance and honestly, I'm shocked you didn't notice difficulty spinning the crank by hand after assembly. There would have been noticable resistance. You need to tear down the bottom end and mic everything again. I personally would not re-use those rods. Better pray your crank journals are not scored and it's salvagable.

 

[forcefed86]

Like said, the caps are actually cast as one piece and cut in 1/2 to ensure complete roundness. The reason why they are location and orientation specific. Once you install them backwards, you destroy this tolerance and honestly, I'm shocked you didn't notice difficulty spinning the crank by hand after assembly. There would have been noticable resistance. You need to tear down the bottom end and mic everything again. I personally would not re-use those rods. Better pray your crank journals are not scored and it's salvagable.

That was kind of my point. If there were resistance and or damage I would have seen or felt it. Since the motor turned over ok and there is no sign of heat build up then I was thinking I got lucky and the rods/bearings were pretty damn close to perfectly round?

Not that I'm disagreeing with you, I'm sure your right. If the journals were scored it would show up on the bearings/caps/crank as a blackened heat mark wouldn't it?? I see no such markings...

Could I Mic everything without tearing the motor down using plasti gauge with new bearings? Seems easy enough to get to...

Thank you for the input!

 

[99gst_racer]

At the very least, I would have the big end of the rods checked for roundness at a machine shop. If they check out fine, then you lucked out at the expense of a set of bearings.

 

[BogusSVO]

^^^^^ X2 on what GST racer said... have the big ends checked at a good machine shop and replace the rod bearings!

the diffrence between HI and low spec on the rod end rodness is .0007 or 7 tenths of one thousands of one inch a pice of notebook paper is appox .003

no if's and's or but's have the rods checked, or be ready to gamble your engine to spun bearings

 

[pj91gsx]

usually putting the caps on wrong would cause the motor to lock up during assembly. How do you know they are backwards.

 

[forcefed86]

usually putting the caps on wrong would cause the motor to lock up during assembly. How do you know they are backwards.

The mains were on correctly. Crank spun very easily by hand with crank bearings torqued. (the large arrows helped, why couldn't they have done that on the rod caps!) When I installed the rod caps I was looking at another motor and going by the casting marks. The motor I was looking at was incorrect and had pistons in upside down.

Didn't pay attention to the bearing retainer tabs which I installed opposite each other instead of on the same side. (that's how I know I got them backwards.)

Once I bolted the rods on it was very hard to turn. But with a 1/2 ratchet and a 12" breaker bar extension I rotated the engine several times and it seemed to get slightly better. Installed the timing belt and also rotated the engine several times.

I've never built up a 4g engine and I didn't know what was normal. I honed the cyls with a 240 grit flex hone. (which is pretty rough) Spoke to an engine builder friend and he told me there would be quite a bit of friction with that grade of cyl hone from the rings. I thought it was normal... apparently I was very wrong. Lesson learned. Luckily I don't have much money in this build. Just blood sweat and now tears...

Pulled the rod bearings and took pictures, they really don't look to bad off from what I've seen come out of engines. The digital camera really brings out the flaws. I didn't think they looked this bad until I saw the photos.


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.

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

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Random rod journal...

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[jlr2196]

"Once I bolted the rods on it was very hard to turn. But with a 1/2 ratchet and a 12" breaker bar extension I rotated the engine several times and it seemed to get slightly better. Installed the timing belt and also rotated the engine several times."
Just so you know next time, you should be able to spin the engine over by hand using the dampner installed on the crank for something to grab or even a standard length 3/8" ratchet. I always check how much torque is required to turn the engine over with a torque wrench, shouldn't be much more than 18-20 ft/lbs on a 4 cylinder. This is with the cylinder head off of course.

See how the wear is all on one side because the caps were on backwards, those bearings are toast. I would be worried you stretched the rod cap at this point, you may heavily consider taking the rods to a machine shop to be inspected for out-of-roundness of each bore then re-conditioned if needed. The crank will be fine.

 

[forcefed86]

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? Not sure but something isn't kosher. You'd think if it were bearings it would show on the bearings. If the oil pump tolerances were off and the oil pump was binding wouldn't I see it in the oil pressure gauge? Trans turns freely, doubt thats it.

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!

 

[TofastForU_99]

+1 take it out and get it on a stand and take a closer look. Im sure once you have it all the way apart your should be able to see the problem pretty easily if it was making the engine behave that way... GL with the build.. keep us posted.

 

[keltalon]

If the rod caps can be installed either way the service manual would not specify any particular direction therefore if you installed them backwards you will have damage! How did you determine that they were backwards?

 

[dented_coffee]

>.<

Thanks for catching that for me. I really must have read that wrong.

But yes, even rod caps on backwards are bad as well but at least you have soft bearings taking the abuse.

After you put everything together the first time did you make sure the crank would rotate by hand and not bind up?

i second that notion. somewhere on the forms there was a guy who had this problem and it was caused by the cam starting to seize in the head. take the cam caps off and inspect it. the heat caused by the steel to aluminum rubbing might be causeing it to expand and grab. i know that a seized cam will stop an engine from even turning over.

 

[forcefed86]

As stated above, caps were on backwards because the tabs on the bearings were on opposite ends. And I've also stated I pulled all the cam caps, and main bearings and all were good aside from the damage shown in the pics. (not much!)

None of this made sense because seizing motors would show signs of heat on rubbing parts. The motor bore and pistons are STD and the pistons rings were used and on the loose side. This is why none of it made sense to me.

I think I may have jumped the gun claiming the motor seized when warm. It turns over pretty easily even with the plugs in when cold. But this is with the lifters all pumped down. Once it warms up and the lifters are all pumped up it will still turn over with some effort. The starter seems to crank it over just fine, my battery may be a little weak from sitting all this time which caused me to hear it drag a bit. Also the starter is used and who knows how many miles it has on it.

Anyway I played around with it a bit more yesterday and it runs now. I think the problem was the SD system!

Once I had the palm logger hooked up I could see my air temp and coolant temp were not functioning. I think the ECU has been shutting down the motor this whole time and not the bearings. I'm glad I pulled the pan and got the bearings corrected though. Once I found my broken wire on the coolant sensor and bought a new air temp sensor (apparently these are pretty fragile) I ran the car for several hours yesterday. No over heating, no "seizing".

I'll still split the oil filter another time and check for metal but I may actually be ok...

 

[byebyev8]

I had a problem similar to yours and the trigger plate was backwards causing the timming to be off. In my case no bent valves.