Connecting Rod Bearing inspection and cap bolts

[d124716]

Hello, I'm planning to drop the pan to do connecting rod bearing inspection and have a question for the group:

1. Has anyone done it with just dropping the pan and without removing anything from the top of the engine? Any words of wisdom on that?
2. On some cars it is required to replace connecting rod cap bolts as they "stretch" and are a one time use only. Have you replaced the bolts during your connecting rod work?

Thanks!

[jasond29]

Yes I have done that many times. I have a 2000 and dropped the pan, removed rod caps, changed rod bearings. I know that my rods were fitted with arp rod bolts and I think that is stock so they are reusable.

[GTS Dean]

I removed caps and inspected the 3-4 rod journals twice in 38k miles. I found no problems despite many, many track weekends. I used trap doors in the standard pan. I would recommend borrowing a high quality torque wrench to retorque the rod nuts.

[ViperSRT]

Normally rod bolts are specified to allow 3 installs. First for rod machining, second for rod assembly on the crankshaft and the third for inspection or service. Personally I would replace if inspected more than once. If you have bumped up the fuel shut off speed I would replace at first inspection.

[GTS Dean]

I thought I read years ago the the Gen1 and possibly Gen2 engines used the LA "P" rods from the Direct Connection catalog. Truth, or fiction?

[d124716]

I'm trying to get my ducks in a row before taking anything off. Looking on a dealer's website connecting rod bolts are no longer available. Doing more research I see that I can buy them aftermarket BUT (don't know if this is true or not) aftermarket don't go through the same torque speck as the stock bolts. Last thing I want to do is to get aftermarket bolts, tighten them to the stock bolts speck and have the bearings "over pressed"... by the same token don't want the stock bolts to "stretch" if they are one time use only thus having them not being tight enough.

Do aftermarket bolts go through a different torque speck? Who would know what that spec is?

[Ramtuff]

Stock bolts are ARP. You can reuse them per ARP.
“Are ARP bolts and studs re-usable?
Yes. As long as the fasteners have been installed and torqued correctly, and show no visible signs of damage, they can be re-used. If they show any signs of thread galling or corrosion, they should be replaced. In the case of rod bolts, if any of them have taken a permanent set and have stretched by .001” or longer, you should replace them immediately. See page 29 in the catalog for more detailed information on this critical measurement.”

https://arp-bolts.com/p/faq.php

[d124716]

Stock bolts are ARP. You can reuse them per ARP.
“Are ARP bolts and studs re-usable?
Yes. As long as the fasteners have been installed and torqued correctly, and show no visible signs of damage, they can be re-used. If they show any signs of thread galling or corrosion, they should be replaced. In the case of rod bolts, if any of them have taken a permanent set and have stretched by .001” or longer, you should replace them immediately. See page 29 in the catalog for more detailed information on this critical measurement.”

https://arp-bolts.com/p/faq.php

Good to know! Sounds like no other preparations are needed for connecting rod bearings evaluation. Time to get that pan off and see if there is anything going on down there.

Thank you!

[d124716]

True or False - issue with connecting rod bearings is signaled via low oil pressure?

Thus the question - IF oil pressure is pristine would one suspect (or need to inspect) rod bearings to begin with?

Thank you!

[GTS Dean]

What do you consider low? 35 psi oil pressure is not a major issue on a very hot day with low viscosity oil - as long as it isn't that low at full revs. The rule of thumb is 10 psi per 1000 rpm. I've driven trucks and equipment with Detroit diesels that idle at 8-12 psi, (mechanical gauge) but they bump right up with rpm.

Regular oil sampling and analysis will tell you just about everything you need to know about engine condition. Your motor would likely be showing substantial copper, aluminum and iron as the major indicators of concern if oil pressure/volume was a big problem. Corse's Gen 1 bearings would have definitely shown highly elevated copper.

If you run a small plastic hose down the dipstick tube and use a MightyVac setup into a clean plastic container, you can pull a few oz. of warm oil every few months to check on things. People spend $7/qt for premium full synthetic oil that will easily last more than a year - even with heavy usage and just throw it away after a weekend or 3 months. I can't believe that. I sample my oil regularly and change it when it needs to be changed.

[d124716]

What do you consider low? 35 psi oil pressure is not a major issue on a very hot day with low viscosity oil - as long as it isn't that low at full revs. The rule of thumb is 10 psi per 1000 rpm. I've driven trucks and equipment with Detroit diesels that idle at 8-12 psi, (mechanical gauge) but they bump right up with rpm.

Regular oil sampling and analysis will tell you just about everything you need to know about engine condition. Your motor would likely be showing substantial copper, aluminum and iron as the major indicators of concern if oil pressure/volume was a big problem. Corse's Gen 1 bearings would have definitely shown highly elevated copper.

If you run a small plastic hose down the dipstick tube and use a MightyVac setup into a clean plastic container, you can pull a few oz. of warm oil every few months to check on things. People spend $7/qt for premium full synthetic oil that will easily last more than a year - even with heavy usage and just throw it away after a weekend or 3 months. I can't believe that. I sample my oil regularly and change it when it needs to be changed.

My pressure always steadily hovered around 60 psi at idle and normal driving. I've seen it get to 70 psi after aggressive acceleration but then go right back down to 60 psi. Even had a mechanical gauge attached just to verify everything working correctly. Mechanical gauge showed similar numbers.. +/- few PSI. Running recommended 10W-30 Mobil full synthetic. I've always wondered why my gauge is not as "responsive" to idle vs acceleration, pretty much every video of any other car I would watch the PSI gauge is almost like an RPM gauge, responds very actively. That is what drove me to hooking up a mechanical gauge, I thought maybe I have a bad sender or a gauge itself, but no.... very surprised to see the car keep the pressure as steady as it does...

So yea, with the pressure being at pretty much a top mark I would think engine bearings are in great shape. This was a discussion that a friend of mine and I had regarding the bearings, he was insisting that anytime you have anything bearing related the gauge will be the first tell tell sign.

[Ramtuff]

The problem is that where the sending unit is in relation to the bearings, gauge pressure is not necessarily a direct indication that you have enough oil at the rod bearings. Inspection is the only way to tell, oil analysis will indicate issues but not exactly where. Same goes for pressure.

[GTS Dean]

True. It's so easy to pull the pan and windage tray - even with the engine in the car - that he should go ahead and inspect. It's not running now anyway. It has been pointed out numerous times in the past that the Gen2 Vipers' sending units, or the gauges are highly damped.

[d124716]

I removed caps and inspected the 3-4 rod journals twice in 38k miles. I found no problems despite many, many track weekends. I used trap doors in the standard pan. I would recommend borrowing a high quality torque wrench to retorque the rod nuts.

What would be considered a good quality torque wrench? I see digital torque wrenches out there, can anyone share what they've used successfully and can recommend. I believe the torque value is listed at 62.5 for cap bolts or something along those lines, main factor being the ".5" step that would need to be setup on the torque wrench so I am thinking digital?....

PS
Don't say Snap-on!

[Old School]

At least as important as the quality of the torque wrench is the technique used with it.

[d124716]

At least as important as the quality of the torque wrench is the technique used with it.

May I please get some guidance on this? Love to get some guidance about the methods and techniques used. I've seen folks use thickness gouge between adjacent connecting rods while tightening up the caps to prevent "twisting". I've also heard about recommendations of doing it in steps (like a head tightening process).

[GTS Dean]

Check the manual to see if torque spec is with (likely), or without oil on the threads. Critical fasteners should be brought up to final torque in at least 2 steps - 50% and 100%. Keep the wrench square with the nut, with the least extension length possible and steady pressure at the center of the handle.

[Old School]

The critical requirement when using a torque wrench is that the fastener must be rotating smoothly when the torque is read. You can't read the torque of a fastener that is not rotating, if you do, you're just reading the break-away torque. So, of if you stop rotating early, just back it off maybe an 1/8th turn.

Procedure for torquing rods is have both rods on that journal installed. Tighten both fasteners on a rod to ~30% final torque needed with the specified lubricant. Then each to the final torque required using a smooth rotation, about 3 seconds for a 1/4 turn.

[d124716]

Thank you for guidance, all good notes! Now, I read manual cover to cover, no mention of specified lubricant on the threads, what do you guys use / recommend (if anything)?

[Old School]

Thank you for guidance, all good notes! Now, I read manual cover to cover, no mention of specified lubricant on the threads, what do you guys use / recommend (if anything)?

The standard is straight 30W oil.

[d124716]

Referencing what RamTuff was mentioning early in this thread regarding connecting rod bolts being ARP, below is from ARPs website, has anyone used this Ultra-Torque?

"Do I need lube on my bolts or studs?
We recommend using ARP Ultra-Torque lube to ensure an even, accurate clamp load and to prevent thread galling. This is particularly important for stainless steel fasteners. The lube should be used under the head of the bolt or the bearing surface of the nut and on the threads, unless a thread sealer is used."

[d124716]

Stock bolts are ARP. You can reuse them per ARP.
“Are ARP bolts and studs re-usable?
Yes. As long as the fasteners have been installed and torqued correctly, and show no visible signs of damage, they can be re-used. If they show any signs of thread galling or corrosion, they should be replaced. In the case of rod bolts, if any of them have taken a permanent set and have stretched by .001” or longer, you should replace them immediately. See page 29 in the catalog for more detailed information on this critical measurement.”

https://arp-bolts.com/p/faq.php

Hello RamTuff, is there a visual clue as to what sets ARP bolt apart from anything else? How would one be able to tell for sure that the bolts he is looking at are ARP indeed? Just in case someone as been fiddling with the cap bolts before and used something different (highly unlikely but you never know) I would want to have some way to verify that the bolts I am looking at are ARP.... is there a way?

Thanks!

[Old School]

ARP bolts are clearly marked ARP on the top of the head.

If they are ARP, I'd use ARP's torque spec and lube.

[d124716]

I've just called ARP and chatted with someone there. They do not have ARP connecting rod bolt for viper currently and the guy couldn't tell me if they ever did. I at least wanted to find out if he can give me the spec...

[Old School]

I've just called ARP and chatted with someone there. They do not have ARP connecting rod bolt for viper currently and the guy couldn't tell me if they ever did. I at least wanted to find out if he can give me the spec...

I can confirm my Gen3 has 'em...

If they say ARP 2000 on them, the torque is 50 ft/lb with their moly lube.