Built motor, instant rod knock, Advice going forward?

grimreaper

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Jul 2, 2008
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my built motor has rod knock after 20 minutes and 2 miles of run time.. primed oil system and verified via oil pressure gauge and turbo oil feed. Had great oil pressure on initial start up, still do just sluggish compared to rpms. generic 5w-30 was used with new filter that was filled before install as well. Had 6 quarts in the sump at start up and when drained. First time the motor had a load on it (pulling down the alley) and I crossed 2400 rpms it knocked.. crank pulley is tqed, pulled the trans covers, nothing loose. Everything was tqed with a torqued wrench. Dropped all the belts thinking ac idler or something but once it gets a load on it, it knocks..

The shop that built it has a reputation to keep and has done 7m's since they came out in the 80's (word of mouth from other 7m owners is not good, other motor platforms seem to hold them in high regards). They want to see the motor before any agreement for repair. This is expected and they have agreed to me being present when they tear it down (It will be torn down when I bring it, no dropping it off and coming back later). I have a build sheet 3-4' long with the work they did, what I spec'd and what I wanted done. Total was roughly $1800 which included them assembling the bottom end. Everything new except the crank and block. Aux shaft was reused but checked and had new thrust plate and collar installed.

My concerns are how far they will go to repair the motor if it was their fault. From a business stand point I foresee the minimal amount of work it requires to get it right but do NOT feel comfortable with this. I'd expect a full tear down, cleaning and starting over. Cleaning be the key here.. rings replaced, and bearings replaced at their cost.
Is this ^ expectation reasonable?
what should I expect if not?
Should it be re-ringed and honed?
Anything else that would wipe a bearing this quickly?

If this was your motor, your $4k+, your time.. would you let them do the repair and walk away confident it would last? any experience to support why or why not?
 

Mk3runner

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Nov 19, 2006
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I'd be there when they crack the caps loose so you can see what they see. leftover metals in the crank could cause quick rodknock, that and many other things. sorry for the engine issues man.
 

GrimJack

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Bearing clearances too loose? New oil squirters? Crank oil galleys cleaned?

I don't know if I'd personally go any further than finding / fixing the fault and replacing the bearings... but I'll freely admit, I've never been in your shoes.
 

grimreaper

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^ what about the rings?
rods where .0012" on the bearings. Yes, brand new squirter's from toyo. Dont know if they cleaned the crank. They polished/cut it to fit the clevite bearings.. They did finale assembly on the bottom end. I picked up the assembled short block ready to run.

IIRC adjusters lasted a few hundred miles with sand running through it. I know each motor is different but how much dirt/metal would it take to wipe it out almost instantly?
 

Mk3runner

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if they didn't blow out the crank of all the metal shavings it wouldn't take long to eat up the bearings. but there are a number of things that could go wrong if your not clean about assembly or measurements. you just wont know until the pan is off and the caps are off.
 

GrimJack

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grimreaper;1618138 said:
^ what about the rings?
rods where .0012" on the bearings. Yes, brand new squirter's from toyo. Dont know if they cleaned the crank. They polished/cut it to fit the clevite bearings.. They did finale assembly on the bottom end. I picked up the assembled short block ready to run.

IIRC adjusters lasted a few hundred miles with sand running through it. I know each motor is different but how much dirt/metal would it take to wipe it out almost instantly?

Depends on the cause. For instance, if a single bearing had a fault, or was installed with too much clearance, it wouldn't cause damage anywhere else, therefore replacing just the bearings along with a nice polish on the crank would suffice.

If, however, it failed due to sandblasting media in the oil, like Adjusters, then you're looking at damage to pretty much everything, and you'd need to replace a lot more, including the rings.

It's all going to depend on what caused the problem...
 

grimreaper

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I understand. There shouldn't have been any media blasting done, I didn't pay for any! Just machine work , sizing and assembly.
 

grimreaper

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Motors back out with a date at the shop on Thursday. The builder is staying late to tear it down while I'm present. Cant ask for much more at this point until we can see what happened and assign the blame.

Received what I feel is the most sound advice... find the problem, assign the blame, and see what the machine will offer or do. If its going to be like sending my burger back at burger king to get the repair done, I'll look else where. (think pissed cook, extra spit etc..) If they are looking to help and toss me a bone, I'll let them fix it.
 

CajunKenny

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Nov 15, 2007
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Glad you were able to get it pulled in a timely manner and get them to respond.

On the brighter side, at least this happened now and not a year from now with 12k on it.

Good luck on Thursday!
 

grimreaper

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good news so far, the shop is going to cover the repair. Bad news is nothing obvious. Rod bearings look good with no wear but the mains had some wear on the middle of the bearing on the bottom shell. They are going through every aspect of the motor at this point to get a big picture of what might have caused the wear. Good thing is the builder is very determined to get an answer on the wear marks and wants it back on the road. Its a family owned/run shop that said they hate the rapport performance shops are giving the industry locally. "if it messes up, tough. welcome to the performance scene" They don't want to be known like this. Promising so far!

The rattle may have been from pre ignition with 2 month old gas (who knows how long it sat in the service stations tanks). Bores also had a brown/rust color ting to them. You could see the marks where the piston had been resting before removal. Maybe condensation in the gas tank. Hard to describe a knock/rattle when everybody perceives it a bit differently. Never heard pre ignition before so nothing to compare with. Something happened to the oil psi before I yanked it though. It was damn near 1:1 with rpms on increase/decrease. It became sluggish before I removed the motor. No metal in the OP or wear in the OP either. Good news.

Update soon
 

grimreaper

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Rattle/knock was detonation most likely from old gas. (ignorant ears on my part) Small signs where found on plugs, head, piston and bores. Plan is to sleeve the block to keep the current pistons and tighten up the clearance a bit more. Going to open up the rods a bit to .0018-.0020 and cut the crank 10 under. New oil pump relief valve had a few areas that were not sealing 100%. They are going to fix that and cover all machine work. I'll pay for the rod/main bearings and sleeves at shop cost.
 

suprarich

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Nov 9, 2005
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call me again Grim if you need any more help. The center wear on the main bearing might be from the main bearing housing hole being too tight for the clevite main bearing. If the housing bore was bored too small, then it will squeeze the main bearing at the points that they touch, which will cause them to deflect and rub the crank.
 

grimreaper

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Rich I called but your voicemail is full :D, I'll try again over the weekend or monday. Going to pick up another HG from you in the near future.