Opinions on rod knock

[dsm-onster]

Ok my friends 1997 ALL STOCK Talon TSI is knocking on the #2 rod. We pulled plug wires until the knocking stopped to veryfy this. It ws driven about 10 miles like this. There is very, very, very fine metal grit in the oil when I dropped the oil. Not much grit either. Also, that cylinder registered 20psi less than the other 3 on a basic compression test.

He's gotten a set of bearings for me to "throw in". He really wants the car back on the road. I'm selling him my 18g and 650s. He has an SAFC, AFPR, walbro 255hp, and a water injection kit. Also he has a BS eleminator kit coming in the mail. He looking to get around 300-320 to the wheels.

I know that, at the least, I should polish the crank at the #2 journal. Is it worth it to do this and put her all back together to see if this will be the end of the problem? If this reoccurs, then I am assuming that the engine has to be pulled to remove the crank, right? What are the chances of this reoccuring? If he has to return the crank, would it be worth it to at least add 1g rods to the short block? where should we go with this thing? He just bought the car this past week for 3500. The body is in excellent shape (good paint, very few dents, he loves this body), leather interior (excellent shape).

He eventiually wants to "go nasty" with this. He's really impatient. He wants it back on the road as soon as he can get it. He wants the BS eleminator kit installed. Would it be easier just to remove the engine? And since it is out woud it be better just to drop the crank and get it properly checked out? Where should we take this thing?

 

[ECLIPSE4x4]

I had the same thing happen to me. I tried the easy route and did what you said. Polish the journal and replace the bearing. Well not long after it came back.

I would reccomend pulling the motor and starting a full rebuild. You will thank me in the end. The odds of just replacing one bearing and it working is slim to none.

Also think about all that bearing material that has cycled through the motor and oil pump.

Pull the motor, just my .02

 

[boostedinaz]

Agreed.


It is understanable that he wants it now, but doing things half ass'd always comes back in the end.

If he wants to "go nasty" as you put it then he will definatly need a good rebuild so why not do it now.

 

[dsm-onster]

That's as bad as I was supposing... He keeps saying "but I just spun a rod bearing. Why are you saying do a full rebuild?"

 

[fallenauthority]

I spun a rod bearing about a month ago, I replaced all the rod bearings to be safe and 3 days later it spun again. So right now im building up on a shortblock from slowboy and im just driving the motor on a spun bearing till i can swap in the new motor.
Just rebuild it and save you and him the trouble.

 

[ECLIPSE4x4]

Well let him do it then. The you can say "I told you so" a month from now.

 

[boostedinaz]

Well let him do it then. The you can say "I told you so" a month from now.

Exactly.

If he wants to do it half assed then let him do it. When it ####s up let know that he just wasted money and time.

 

[dsm-onster]

Hehe, yea. Hey! don't think ill of him he's my friend. I just don't think he understands that all that metal from the bearing/crank is floating around all over the interior surface of the block. And how critical it is for the crank to be exactly true at the journal. He!! I didn't even really know this much about that until I researched this (never spun a bearing in any car I've ever owned). But yes, I think it will be to his benefit greatly. If he doesn't waste his time/money with just slapping a set of ring in and going on. He's paying me for this. So I don't want to ahve to go back in there after I rebuilt it and do it right. He's my friend. There would probably be some "payment" wierdness there. Besides I really don't mind giving him a deal with my work. I am an ameture at this.

Anyone know where/if I can ship this crank to to get it checked/turned/polished. We live on the eastern shore penninsula of VA. There's nothing out here but farmers and trailers. Price is a priority. I know SBR will give you a remanufactured crank with the matching bearings. But I'm sure the $350 pricetag is out of his budget right now... Is this a good price?

 

[sho_tyme_psi]

If he does decide to do a dirty rebuild, atleast make him change the oil a few times the first week. Best of luck to him.

 

[dsm-onster]

Yea, he's talked to his dad (rebuilt a few old v8's) and his uncle (done the same). They both tell him that this is not metal grit but the nitide from the crank or the surface material used to harden it... what ever they think it is. They say that the bearings are made of much softer material than the crank and that a deep enough score not that you can't polish out is highly unlikely with about 10 miles on the spun bearing. They said to flush it out. I guess that means change the oil alot after you polish the one journal and drop the new bearings in. I told him that At least he shuoldn't run the new 18G that I am selling him. So we agreed to put the old T25 on. He said that his wife is really disappointed. "She hasn't even driven it yet." So he's insisting that I just polish the crank and throw the bearings in. He says he trusts his dad and uncle more.

 

[boostedinaz]

He said that his wife is really disappointed. "She hasn't even driven it yet." So he's insisting that I just polish the crank and throw the bearings in. He says he trusts his dad and uncle more.

It will most likely be a short journey and the wife will have to wait longer. Live and learn I guess.

 

[ECLIPSE4x4]

Well that about sums it up. Tell your friend good luck.

If I were you, I would refuse to do half assed work on his car. If you do it knowing it will not work, you will be just as much at fault.

Make the right decision.

 

[pneumo]

That's a sticky situation to be in. You know it won't work, but your friend and his elders say it will. So they order you to do the work anyway.

What you need to do is CYA. Inspect everything in the motor and look for anything that would make a new rod bearing fail again. Inspect the crank journal carefully. If you're lucky it will be totally thrashed and you won't have to continue the work, you can just say,'see? it's not salvagable. told you so'. and your friend will have to get a new crank.

If the crank is OK, then look at the big end of the rod. There should be obvious machine marks inside the big end. If the machining is ground away by the spun bearing, the rod is garbage and will need to be replaced.

Plastigage the new bearing in several places to make sure the clearances are OK. If not, stop.

Good Luck.

 

[dsm-onster]

Well that about sums it up. Tell your friend good luck.

If I were you, I would refuse to do half assed work on his car. If you do it knowing it will not work, you will be just as much at fault.

Make the right decision.

A timely suggestion that I obviously need to follow. thanx. I appreciate your help. A true friend saves another from himself .

 

[dsm-onster]

That's a sticky situation to be in. You know it won't work, but your friend and his elders say it will. So they order you to do the work anyway.

What you need to do is CYA. Inspect everything in the motor and look for anything that would make a new rod bearing fail again. Inspect the crank journal carefully. If you're lucky it will be totally thrashed and you won't have to continue the work, you can just say,'see? it's not salvagable. told you so'. and your friend will have to get a new crank.

If the crank is OK, then look at the big end of the rod. There should be obvious machine marks inside the big end. If the machining is ground away by the spun bearing, the rod is garbage and will need to be replaced.

Plastigage the new bearing in several places to make sure the clearances are OK. If not, stop.

Good Luck.

Yea based on ECLIPSE4x4's sugestion, I am going to do it exactly the way you say. I think that if there is ANY scoring at all I'm going ot tell him that all he can do is pull the crank and get it machined... And then I'm going ot point to the THOUSANDS of posts about broken turned cranks. I'll leave it to him how much horsepower he wants to dump on a turned crank. He has a goal and he certainly won't meet it once his crank is turned. When he said he wanted to "go nasty", he mans that he wants to go to the limit of a good 7-bolt. He will have dropped that limit to below his expectations if he choses to turn his crank. Either way, that will get the crank out of the car so that a profesional can measure it and determine for sure whether the crank has to be turned to be useful. Once he reads the posts on broke turned cranks, he'll get it that turning a crank is no good for 400 hp applications and he simply must get a new crank to reach this goal. I hope he reads this soon. He's gone to florida now. HAHA! he was hoping that I could get his car up and running with my old 18g 650s and HIS safc INSTALLED NOT GONNA HAPPEN NOW!!!