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Engine main bearing housing repair

Amateur64

Plastic
Joined
Sep 25, 2022
I would like to seek advice on the following matter. I apologize if this is not the right forum but I cannot find anything on the internet. I hope to get the opinion from those have the experience and knowledge.

I bought a used engine block from Europe to replace the one in my car. After receiving the engine block, the second main bearing housing was previously repaired. It was also missing a slot for the main bearing.

I have never come across such a repair before. My main concern is whether the repair is acceptable (see attached photo). Can it withstand the load and vibration of the engine?

Secondly, as the slot for the main bearing is missing, is it all right to grind off the locating lug on the main bearing in order for it to fit into the housing?

Thank you for your attention.
 

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cudafamily

Aluminum
Joined
Oct 31, 2013
Location
Evansville, IN
Sort answer is NO and NO. Your picture does not show the actual damage that the 2 screws are holding together, but it can't really be that strong to support the forces a crankshaft sees when in operation. It's also on the thrust bearing for that engine, which means that bearing block must support lateral movement of the crank. The bearing tang not only locates the bearing but also offers a resistance to spinning.
If this is a rare are hard to find block, I would take it to a reputable rebuilder and have them take a look and see if it is reparable, and at what price.
 

john.k

Diamond
Joined
Dec 21, 2012
Location
Brisbane Qld Australia
You can easily file the slot for the bearing tab...........looks like the bearing has spun ,and the block cant be repaired by a face off the seats and an align bore..............I have a GM 6V71 block where a main cap bolt has broken and pulled a piece out of the bearing bore.............repair is possible,I have simply junked the whole motor.
 

GregSY

Diamond
Joined
Jan 1, 2005
Location
Houston
I agree you need the locating slot. I'm curious just how it was 'repaired'...JB Weld or?

In any case, I'd add the slot back by using a Dremel tool to remove most of the material then (probably) hand files to finish it. No way would I grind off the tab on the bearing insert.
 

gbent

Diamond
Joined
Mar 14, 2005
Location
Kansas
Done well, that is a perfectly acceptable method of repairing an engine block. The little information I can see from the picture gives me little confidence in the job. The insert appears to be installed at an angle, there is cam out on the screw slots, and the bearing tang slot was omitted. Poor appearance suggests poor workmanship.

Tell us more about the engine and the car, and your intentions for the car. If its a 50 mile/year garage queen the repair may be adequate after cutting the tang.

This forum has an expert engine builder/restorer/magician who goes by AlfaGTA. Perhaps he will be along.
 

michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
I would likely set the crank in and blue it in to be/inspect for in line with other mains, it needs be near dead line straight. if the line bore is .001 out of straight or off center line it will be a crap fail engine needing excessive bearing clearance to not rub the bearing.

I used to finish grind the Barber Coleman reamers for the line bore of mains, we mostly held them to one-tenth. We did them on a Cinci #2 with bumping and counting sparkes and measured with an indicator micrometer to a gauge block that wa temperature controlled(very close work). Then they were set on a line-bore off an engine's other mains. (agree the #2 was not the best grinder for that job, the B&S 13 or other OD grinder would have been better)

The lock slot will have to be very close end ways to locate the crank, and allow proper thrust clearance and location. Likely that could be done by a very skilled hand or mill operation. likely .001 accuracy would be OK.

Thrust location is important or you may end up with a rub someplace
 
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howieranger

Aluminum
Joined
Jan 24, 2007
Location
Mountain Home AR.
Done well, that is a perfectly acceptable method of repairing an engine block. The little information I can see from the picture gives me little confidence in the job. The insert appears to be installed at an angle, there is cam out on the screw slots, and the bearing tang slot was omitted. Poor appearance suggests poor workmanship.

Tell us more about the engine and the car, and your intentions for the car. If its a 50 mile/year garage queen the repair may be adequate after cutting the tang.

This forum has an expert engine builder/restorer/magician who goes by AlfaGTA. Perhaps he will be along.
I agree that the workmanship is very poor and should not be used even if you can cut the bearing locating tab. What does the other half of the crankcase look like and has it been repaired? Do you have the means to measure the diameter of the bore and wether it is in line with the rest of the case. I would think that you would be better off finding another case that has not been bodged together. I would think that having a competent shop weld up that bore and then align bore it would be cost prohibitive.
 

Amateur64

Plastic
Joined
Sep 25, 2022
Thank you for your comments. Much appreciated.

My guess is that the main bearing housing was damaged. Repair was carried out by shaving off the damage and putting in an aluminum insert. The two screws hold the insert in place. I worry whether the screws are strong enough to withstand the engine load and vibration. The car is for normal daily use, not for the track.
There is nothing wrong with bearing cap.
The engine block is aluminum.
The car is an Alfa Romeo 164 2L Twin Spark (4-cylinder).
 

GregSY

Diamond
Joined
Jan 1, 2005
Location
Houston
Wow, now I see what they did...pretty lame. OK..if it was me, I'd shove that block up the ass of whoever you bought it from. Since they are in Europe, that might be hard to do given COVID restrictions.

If I had to use it...I'd have someone who knows what they are doing weld all of that area back. Then I'd have someone else who knows what they are doing machine it back to stock specs, tab slot included.

There are people who can do this...you just have to seek them out. I'd start with the guys who repair the Top Fuel Hemi blocks that get windowed all the time and welded back together. This might be the Top Alcohol guys who are too broke to buy new blocks and feed off the Top Fuel guys' scraps.
 

ratbldr427

Stainless
Joined
Mar 21, 2006
Location
jacksonville,fl.
The major load is on the main caps,on compression or firing. An insert in the upper half of the block properly installed and align honed or bored will not cause any problems what so ever. PROVIDING that the block has enough wall on the upper half of the webb to support it. Varies by block.
Example is the use of bearing inserts in 400 sbc's to install small journal cranks. Of course it's not ideal but have seen many that never failed putting out way more hp than oe ever planned for. Difference is they are iron blocks and this is aluminum.
Due to thermal expansion I can see why the installer used an aluminum insert but thin aluminum insert would deform more than steel . Otoh it is in the middle of the block which is good.
Since it is a somewhat rare block I would take it to a reputable rebuilder and have them check it out and follow their advice. Any way the fact that it has an insert for repair is not a big deal and for his use will not be anything to worry about.
 
Joined
Nov 19, 2007
Location
marysville ohio
What ratblder 427 says is true, I de-stroked a shit ton of 400 inch blocks with bearing shims and never screwed one in place. I would never consider welding an aluminum block in the main bearing area, aluminum goes dead soft when you weld it, you have stud / bolt threads that will end up soft. A rod window is fine to weld as it is far from anything that matters. Do not grind the tab off the bearing, machine the insert for it.
 

michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
You could (?) snub the tabs off a set of shells, and assemble the bottom end with .002
shims in the bearing(where the oil goes) to see if it locks up. If it locks up then likely the block won't be good. Yes, the rest of the assembly has to have shells installed to make this check.

Or turn a main journal gauge and plate check the block. Not much sense notching it if the location is off.
 

PackardV8

Hot Rolled
Joined
Jun 4, 2006
Location
Spokane, WA
Interesting that everyone agrees the alignment (it's not a locking feature) tang and slot must be preserved. Sounds right, but it's not.

Count me as having built engines for sixty years and do many obsolete engines which require making other bearings fit when the originals are NLA. Straight from Clevite/Mahle, "The tangs and slots are only for alignment. It is the designed-in crush which locks the bearings in the bores. Many recently designed engines assembled by robots, the bearings and bores have no tangs."

jack vines
 

Garwood

Diamond
Joined
Oct 10, 2009
Location
Oregon
I think my hillbilly test would be to install new main bearing shells in all the main bores. Then I'd measure all of them. If the repair is the same as the rest with the bearing squished under the torqued cap, I'd be OK with the repair. I'd think if the repair was bodged the bearing's bore would measure a thou or two big where the repair was done.

If that insert were in there without any screws, just a dowel pin or spring pin to locate it, the main cap alone would keep it in place if it were done right.

I wouldn't be bothered to run a bearing shell without a tang, but I also wouldn't want to grind one off perfectly. I feel it would be easier, less chance of a big problem, to add the notch to the repair insert.

It's hard to measure straightness of mains. Trick I was taught is to put a dime size spurt of lubrip0late on each bearing. The coat the main journals with 30wt. Install crank, torque mains and give it a good spin. If the clearances are correct and the crank spins effortlessly the mainline is good enough to run.
 

john.k

Diamond
Joined
Dec 21, 2012
Location
Brisbane Qld Australia
Surprising there is no oil hole in the main.........anyhoo ,its easy to check the few things that a motor needs......bearing crush,check the crank for straightness ,then you can blue and install the caps and see if things are running evenly..............My old man rebuilding a GMC 270 truck motor....... shims in both mains and rods .........the starter wouldnt turn the motor over,he had it so tight ,had to tow it with a tractor to get it to start...........he always used to reckon its no use having a half worn out motor............which was BS,because you could drop the sump and pull shims anytime the oil pressure dropped.
 

boslab

Titanium
Joined
Jan 6, 2007
Location
wales.uk
I have seen a similar repair on a 16 cylinder rolls Royce inline locomotive engine , considerably bigger and had dowels in, screws seem pointless to me, as the thing can’t lift once there’s a shell in?
Not an expert by any means not done much engine work
Mark
 

johansen

Stainless
Joined
Aug 16, 2014
Location
silverdale wa
With no oil passage to the bearing I think it will fail, unless you can get enough oil to that bearing through the crankshaft. (Which isn't going to happen above a certain rpm since centripetal force wants to push it out the other direction.)

I find it concerning that they appear to have gotten the width of that shell correct but it's cocked sideways, proud on top left and bottom right.

That being said I disagree that the main bearings have to be in a straight line.

My brothers vw Jetta 1995 gas engine, 2 liter I think, we figure it had overheated on the prior owner, the engine had so much friction you needed a breaker bar to turn the engine, and it was clearly the camshaft where all the friction was. Once the engine was running, the oil film dropped that friction to near zero. Car ran that way for at least 50K miles.

A crankshaft is about 8 to 16 times stiffer than a cam shaft (given that it is usually about twice the diameter) and as such will only take .001" to "not turn smoothly". But that is not enough misalignment to apply a damaging constant load on the crank. Now obviously if you need a breaker bar to turn the crank then yes you will probably spin the bearings on startup. But if the bearings reliably handle the load at startup, then a few hundred pounds force needed to distort the crank by .001" isn't going to be noticed compared to thousands of pounds of force of combustion and compression.
 
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Ralph_P

Stainless
Joined
Jan 14, 2003
Location
E. TN USA
Whoever did the repair has already align-honed the block. The screws were needed to keep the shell in (correct) place before and after the repair.

He didn't have the bearing shell, so he left it to the owner to cut the notch for the bearing tang.
 

GregSY

Diamond
Joined
Jan 1, 2005
Location
Houston
Interesting that everyone agrees the alignment (it's not a locking feature) tang and slot must be preserved. Sounds right, but it's not.
I was going to say the same thing, but I didn't. Why? While I recognize the crush is going to hold the insert in place, It also recognize the tang serves the function of keeping the insert in axial alignment, especially during assembly. Without it, it imposes a greater burden on the assembler to ensure (not insure) the edge of the insert is not riding on the radius of the crank journal. Can it be done? Yes. But it's treading into the Shaky Zone when adding back the proper locating slot/tang will be doing it the right way.
 








 
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