Con rod Failure 3.0 V6 - Alfa Romeo Forum
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(Post Link) post #1 of 26 Old 05-11-11 Thread Starter
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Con rod Failure 3.0 V6

Hi guys, I`m new in here so sorry for bad English or other mistakes I will make

Some time ago I bought a 3.0 from 98 GTV and putted into my 156, but when We were installing it I saw that something was made with it so We take out the oil pan. The Crank was grinded and the bearings was 0.10 con rod and 0.20 main ;/ but there was no time to go back so ... engine make about 8k km and con rod bearing failed at high rpm... I bought another Crank from Alfa 166 but need some technical data for it, like main journal diameter min and max and con rod journal diameter, thanks for any help! I will post some more info about working on that engine.

PS. Here`s the link to Polish Fan Club where I`m posting some pictures ---> Remont 3.0 V6
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(Post Link) post #2 of 26 Old 07-11-11 Thread Starter
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Ok, noone helped Me but I found the answers :P, but...

My crank have:

Main journal diameter:

59,975 Nominal - 59,961-59,979
59,975
59,965
59,950

and connecting rod journal diameter:

51,975 Nominal - 51,980-52,000
51,975
51,970
51,980
51,950
51,980

Can someone explain to me the big diference in those 2 bolded?
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Alfa crank journals were often different sizes, that's why you will often see different grades (colour) of bearings fitted on the same engine from new.

If you are ABSOLUTELY sure it's not wear, then it's not a problem, you just need to pick the right bearings.
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(Post Link) post #4 of 26 Old 08-11-11 Thread Starter
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so it should look like this?:

Rod:
51,975 B
51,975 B
51,970 B
51,980 B
51,950 B
51,980 B

Main
59,975 A
59,975 A
59,965 C
59,950 C
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The bearings are colour coded from alfa. Unless you have the original details from the car the new crank came from you won't be able to get any from them. You have to get customs made. When I damaged th carnk on my TS engine I had it ground with oversized bearings to match. Was fine after that. One thing to note with grinding the crank. It has a toughened layer on it so when they are reground you must be careful not to go through this layer or you will have the same problem as the crank itself will wear out

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Quote:
Originally Posted by ChrisS View Post
Alfa crank journals were often different sizes, that's why you will often see different grades (colour) of bearings fitted on the same engine from new.

If you are ABSOLUTELY sure it's not wear, then it's not a problem, you just need to pick the right bearings.
This is true.
On 2.0 TS I have CCCC (or 3333 to be precise, Alfa also uses numbers on TS engines) on rod journals.
Not only that, but on main, two of five were OVER 53,000.
53,006 and 53,009 if I remember correctly.
This numbers were not measured by me, but they were printed on crank by Alfa.

Last edited by Boris; 09-11-11 at 15:56.
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(Post Link) post #7 of 26 Old 09-11-11 Thread Starter
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Guys I said that I got another crank and writen the sizes of each journals. Old crank is going to junk. I know about the colours but on eper it shows groups A,B and C. On my last post there are diameters of the "new" one and groups that I compare for someoone who could check them are they right. Cranks can`t be grinded in V6 to oversize... You can check the link from the 1st post what hapend after someone did it on it.
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The bearings are colour coded from alfa. Unless you have the original details from the car the new crank came from you won't be able to get any from them. You have to get customs made. When I damaged th carnk on my TS engine I had it ground with oversized bearings to match. Was fine after that. One thing to note with grinding the crank. It has a toughened layer on it so when they are reground you must be careful not to go through this layer or you will have the same problem as the crank itself will wear out
All original factory measurment for crank are printed on "phonic" wheel on crankshaft (at least on TS).
Color codes are very hard to read on used engine because they are often washed out by aggresive oil.
Anyway, original measurment is not very important for used engine with high mileage, crank has to be measured anyway...

Alfa sells oversize journals for TS, but not for V6. Oversize for grinding on TS is 0.127 mm, but on V6 it says that "The nitriding treatment applied to the crankshaft does not allow grinding operations to be carried out"
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Originally Posted by BaMboSzeK View Post
Guys I said that I got another crank and writen the sizes of each journals. Old crank is going to junk. I know about the colours but on eper it shows groups A,B and C. On my last post there are diameters of the "new" one and groups that I compare for someoone who could check them are they right. Cranks can`t be grinded in V6 to oversize... You can check the link from the 1st post what hapend after someone did it on it.
1.Did you measure the diameters or read it from the crank?
2.the bold numbers look very bad....under the C class. (or B for rod). You should ask for opinion somebody with bigger experience with V6 engines...

I think that A, B, C classes you wrote are ok (only question that remains is the bold numbers)
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1. I measured them.
2. The other crank I got have main, 59.3++ and Rods 51,5++ so its huge diference, but it was grinded...
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1. I measured them.
2. The other crank I got have main, 59.3++ and Rods 51,5++ so its huge diference, but it was grinded...
1. Then It is OK.

For the bold numbers... if there are no signs of wear, C for main and B for rods will probaly be fine... but I were you when you get the journals I would measure everything with Plastigauge at the end just to be sure that there is no too much free play on the journals especialy on the "bold" ones.

https://www.alfaowner.com/Forum/motor...oce-6c-11.html

Also you can check if there are any aftermarket journals with something like C class for the rods...or similar for the mains.
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Thanks!!! so the best play should be 0,035-0.065?
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Thanks!!! so the best play should be 0,035-0.065?
My data says:

rod journal 0.034 0.062

main journal only!! 0.000 0.025
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Plastigauge them for sure when you do a dry assembly.

Not that I have done that many, but I always used TS main bearings on the V6 (the wider shell used on bearings 1,3 & 5 on the TS IIRC) - they are slightly wider and slightly tighter than the equivalent V6 shell. Also, you have to stick with the V6 shell on one of the mains - can't recall if it's 1 or 4, but it's obviously different anyway...unless my memory has totally gone!
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Plastigauge them for sure when you do a dry assembly.

Not that I have done that many, but I always used TS main bearings on the V6 (the wider shell used on bearings 1,3 & 5 on the TS IIRC) - they are slightly wider and slightly tighter than the equivalent V6 shell. Also, you have to stick with the V6 shell on one of the mains - can't recall if it's 1 or 4, but it's obviously different anyway...unless my memory has totally gone!
TS bearings on V6????
They have different diameter...!

About diferent bearings, TS have different main bearing on 3 because of axial bearing.
1,2,4 and 5 main bearings are the same.
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Yes, TS bearings from the 164 range. The 'NORD' engine as the Americans call them I think?. I sold the car with the V6 in it a while ago and all the paperwork went with it, or I'd be able to give you the part numbers I used...but yes, definately TS shells. Slightly thicker and wider than V6 parts, give better (smaller) clearance and a wider (by about 3mm) bearing.

Can only use RED or BLUE mains (given the correct figurs of course), YELLOWS are too thick/wrong size entirely. I've even seen an analysis where one main has a mix of one red and one blue shell. Apparently only REDS & YELLOWS are available from Alfa now too, so it's REDS or nothing.

The engine version I'm talking about has the same part number for main bearings 1,3 & 5...so I guess we are talking different versions here.

I wish I had the data to hand, as I realise it sounds a bit dodgy without it!

Whatever you do, do be sure to trial assemble and measure with plastigauge.
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OK, had a brainwave and recovered an old e-mail archive.

The shells I used for my last V6 build to replace the original REDs were 60585438. (The correct V6 part was 60568882). I used a full set of 8 half-shells (all 4 bearings).

They are listed for the 75 (1988 - 1992), the 155 (1992 - 1996), 164 (1987-1997) and the P6 & 8 Spider (1990-1993)

...and are most definitely for main bearings 1, 3 & 5 on that engine. That version uses seperate half rings to control crank axial play, much like the V6.

Hope that clarifies it - I don't want to be putting duff info on here!

Again, to absolutely bang it home...I did a test assembly and checked all the clearances with Plastigauge!!!

Hope that's of some help.
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(Post Link) post #18 of 26 Old 23-11-11 Thread Starter
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Ok, another question :P I honed the liners but pistons are bit loose, can I install them with bigger rings? I recorded the piston free play --> Lu
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Don't bigger rings mean bigger pistons?
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Don't bigger rings mean bigger pistons?
You can buy oversized rings.
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Only real way is to measure....if bore and piston are in-spec...then go ahead. Probably wise to get total seal rings and gap them yourself in that situation though.
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That doesn't look right to me, I think oversize pistons are required.
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That doesn't look right to me, I think oversize pistons are required.
Fiat don`t offer oversized pistons... ;(
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Replacement liners then? Take the bores back to standard.
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Originally Posted by gazza82 View Post
Replacement liners then? Take the bores back to standard.
In that way I could change whole engine to brand new... but it`s not about that. Anyway I getted bigger pistons from 166 and they are tighter
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