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Discussion Starter #1
I noticed a slight droning sound on my GTV on two occasions. It is apparent under load and above 2500rpm and goes away at idle or under light load. I first noticed it just before going on holiday 2 weeks ago and thought it was the exhaust. After inspecting it on a lift, I think that the noise is coming from the sump area of the engine.

Does this sound suspiciously like a main bearing knock? :paperbag:

Could this be related to my cylinder head that blew in November? There was no water in the oil. The heads were removed and the engine was serviced completely including water pump, belts, tensioners, idlers and valve lifters. At the time, the bottom end seemed solid and a compression test proved that the rings were still perfect.

I haven't noticed any low oil pressure or loss of oil.
 

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That does sound suspiciously knocky :furious:

You can put the car on a lift and drop the sump for inspection on play on conrods and metal shards in oil pan - that would be my best advice for the least intrusive / money gobbling verification

My Alternator bearing went and it sounded like engine pinging at cold start up around 2000 rpm - 2500 rpm and medium load. I know this is not related, just telling a story that hopefully might point your problem elsewhere
 

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Discussion Starter #3
Let's suspect an engine knock... What are the chances of the crank being buggered? They are hellishly expensive!

I was planning a bottom end build on this engine anyway but would have liked to start at the end of the year only so this is a bit unfortunate, but luckily something that I was contemplating.

Can I ask for some advice quickly:
Let's just say that maybe I can get a BRAND NEW CRATE MOTOR!!! (At a secret location for a secret price) :smoker::smoker::smoker:
Should I take it and then build the existing motor into my fantasy race engine at my leisure? :devious:
 

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At this moment in time, no serious harm - at most the bearings are gone with small scarring on the crank. You'll have to polish the crank down 10 thou and fit 10 thou bearings which should be readily available.

Bad case of dropping bearing:
https://www.youtube.com/watch?v=rhDbAp8vXcM
You can do that inspection from the bottom
 

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...about that crate motor... :devious: ???
Can I ask for some advice quickly:
Let's just say that maybe I can get a BRAND NEW CRATE MOTOR!!! (At a secret location for a secret price) :smoker::smoker::smoker:
Should I take it and then build the existing motor into my fantasy race engine at my leisure? :devious:
No brainer - if I had the cash available now - I won't be on AO - I'd be picking up the motor already. You will get your money back later if the secret price is right :xmas:
 

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buy the motor
 

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Ian, are you concerned that the head gasket failure may have been a result of big end play? Due to?, the piston touching the head? This would surely have been evident?
 

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Discussion Starter #9
The secret price: R45k for brand new factory motor in crate, AR932 engine code :biglaugh:
 

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Discussion Starter #10
Ian, are you concerned that the head gasket failure may have been a result of big end play? Due to?, the piston touching the head? This would surely have been evident?
No, I was just wondering if that may be a peculiarity of the engine. There was no contact between the head and any pistons, and besides, it sounds like a main bearing, not a big-end.
 

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IME mains don't knock, but growl or howl, with significant loss of power. They don't have the same heavy knock that big-ends exhibit. Either get worse rather rapidly. Caught early enough you often escape crank damage.

Failing end float bearings can also make similar noise, but usually operating the clutch changes it.

Drop the oil and check for bearing fragments in it. This can be metallic dust up to flakes or lumps of shrapnel.

Clutch release bearing is another possibility. I'd also want to eliminate the recent waterpump, belt tensioner and idler. New parts can be defective.
 

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Ian, Ian, Ian.....

My motor had a bearing knock, that's why i dropped a rods through my sump......but, i drove the car for almost 3 years with the knock, no loss of power just an irritating noise until one day, KABOOM!
 

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Ian just had his top end reconditioned and modified. I wouldn't be able to sleep if this happened to me. I was just thinking now - what if something fell into your block while they were working on your heads? I would want to be present when the sump is dropped.

Sent from my SM-G925F using Tapatalk
 

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No, I was just wondering if that may be a peculiarity of the engine. There was no contact between the head and any pistons, and besides, it sounds like a main bearing, not a big-end.
of course, not thinking straight.

Ian just had his top end reconditioned and modified. I wouldn't be able to sleep if this happened to me. I was just thinking now - what if something fell into your block while they were working on your heads? I would want to be present when the sump is dropped.

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what, past the pistons?
 

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Dunno. Just throwing things at the problem. Because fish curry, bra :D. Anyway, I would want to be there when they drop the sump.

Sent from my SM-G925F using Tapatalk
 

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Discussion Starter #17 (Edited)
Avi I have no intention of driving my car anywhere. She is parked now, which is a shame as I was going to have some mods done, starting with a complete new exhaust, induction and remap to cure the overfueling since the cats were removed.

She sounded wicked though: :devious:

 

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Avi I have no intention of driving my car anywhere. She is parked now, which is a shame as I was going to have some mods done, starting with a complete new exhaust, indiction and remap to cure the overfueling since the cats were removed.

She sounded wicked though: :devious:

Sounds wicked!
 

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Discussion Starter #19
Ian just had his top end reconditioned and modified. I wouldn't be able to sleep if this happened to me. I was just thinking now - what if something fell into your block while they were working on your heads? I would want to be present when the sump is dropped.

Sent from my SM-G925F using Tapatalk
El, I will be there when they drop the sump because I want to see the oil, the thrust washers, big ends and mains come off. Giorgio knows that I am like that. In real life that is what my department at work does. I'll let you know so you can join me under my car.

When the heads are off, nothing can really get into the block unless it crawled between the rings and grew up in there. Or someone pulled the sump and stuck putty on the oil strainer.

I have dropped some nice things in my Nord sump already (most notably a cam sprocket nut and locking plate) and waited 10 years to take it back out and I cannot imagine what damage it was supposed to be causing in there. It lies at the bottom, all cozy and damped by engine oil so it will be going nowhere and doing nothing.
 
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