B18A Engine Block queries

[sleek lemur]

Hi all,

Main bearing.jpg

This is the rear main bearing housing from the B18A I'm rebuilding. I'd be really grateful to hear your opinions on the damage to the outer surface, particularly is it necessary to repair ? From memory, when I dismantled the engine, nothing mates to this surface, does it (the engine was filthy, so I can't be sure!)?

Second question: Would you recommend disturbing the three grub screw oil gallery plugs (2 x 952075 at the front and rear of the block and a smaller one 952069 on the RH side of the block forward of the oil filter) ? They're stuck fast and the square holes feel like they're threatening to round off.

Thanks as always,

SL

[142 Guy]

I am assuming that you are talking about the scoring and nicking on the metal around the opening for the crankshaft journal? I have a B20, not a B18; but, assuming that the B18 is like the B20 it looks to me like you still have the bearing shell in place and that the damage is to the flange on the bearing shell. Since you are rebuilding I assume that you will be replacing the main bearing shells which effectively repairs the damage when you put the new shell in.

[sleek lemur]

Thanks vm, 142. In fact it's a bit deeper than scoring, it looks like some metal is missing. But you're right, when I look at the 5th main bearing, the thrust face mates the polished semi- circle, so my initial reaction is that the damage is not important. Really appreciate your reply.

I wonder if you have any comment on those oil journal plugs? Can I leave them in situ? Am not clear on their purpose!

[Derek UK]

As 142 says, what I think I'm looking at is damage to the side flanges of the main bearing shells. I'd be replacing these on a complete rebuild. Removing the oil gallery plugs is up to you. It does enable you to flush out the galleries if you have the kit to do it. If there is an engine rebuilder anywhere near you you could get the whole block hot tanked with the plugs removed? The plugs may well have had a dab of Loctite on. A blow lamp would soften that up or leave it to the hot tank shop.
Brookhouse - 952075 OIL GALLERY THREADED PLUG (NPTF 1/4") £3.48

[Bracpan]

Originally Posted by Derek UK

As 142 says, what I think I'm looking at is damage to the side flanges of the main bearing shells. I'd be replacing these on a complete rebuild. Removing the oil gallery plugs is up to you. It does enable you to flush out the galleries if you have the kit to do it. If there is an engine rebuilder anywhere near you you could get the whole block hot tanked with the plugs removed? The plugs may well have had a dab of Loctite on. A blow lamp would soften that up or leave it to the hot tank shop.
Brookhouse - 952075 OIL GALLERY THREADED PLUG (NPTF 1/4") £3.48

I have a set of gun cleaning rods and brushes that I use to clean out oil galleries.. plenty of paraffin and use of an airline helps.
But i agree a hot tank is a great benefit.

[blueosprey90]

I'm not familiar with your oil gallery plug situation, but if you are going through the trouble to rebuild the engine, I would pull them. Who knows what kind of sludge and grit is in the galleries waiting to ruin a new rebuild.

On the MGA and MGB engines, the stock oil gallery plugs were brass plugs. On the engines that I have tampered with, I've pulled the plugs and then threaded the holes for a 1/8" or 1/4" NPT plug, depending on location. The NPT taps are tapered, as are the plugs.

My guess is that the factory did use some sealer or locktite to seal the plugs in place. Indeed, I used Permatex on my plugs, but others have used JB Weld epoxy. I would apply big heat to try to free them up. As a last resort, you can perhaps drill them out and then retap to rethread at the next size up.

There are long handled, small diameter hard bristle brushes that you can use to run through the galleries once you open them up. I have a whole array of brushes that I've used and we can get them fairly easily and inexpensively in the States.

In my area, the machine shops don't seem to hot tank in caustic solution anymore - probably for environmental reasons. Maybe more of a pressure wash is what they do. I've tried to clean the engines before taking them to the shop for cleaning, and even before final assembly, I have rewashed the engines. Even after the machine shop treatment. I try to hit every oil passageway. It's surprising how much dirt is left in the bottom of the tub after the final cleaning.

[Derek UK]

I would also add, that if you are able to get it hot tanked or pressure washed it would be a good idea to remove all of the core plugs as well. They are cheap and you never know how rusty they are from the outside. The large side ones allow pressure washing and an air line to remove the sludge. There could be a lot of that. When these go bad it means that to renew them properly the engine has to come out. There is no room to swing a club hammer. There may be such a thing as a air operated hammer gun that can be set to a pressure to do the job properly but I've not seen one.

[sleek lemur]

Many thanks, everyone.

The damage is actually on the block. As 142 identified, this is the polished surface where the new #5 bearing which thrust faces will sit. I will ask the machine shop's opinion as well. For me, it looks like I can get away with it.

ncidentally, he was extremely complimentary of the Volvo red block engines. Also, did you see that when asked what was the most iconic auto item of the 60s, one Practical Classics journalist chose these engines.

As for cleaning, I've been at it for a good three weeks now. I don't have an airline, so will have to entrust the oil journals to the shop. Cylinder head has been soaking in white vinegar this week.

All 10(!) Core plugs are out.

Will get shop to do the three oil gallery plugs before I can cause any more damage.

[142 Guy]

Originally Posted by sleek lemur

Hi all,

Attachment 131591

This is the rear main bearing housing from the B18A I'm rebuilding. I'd be really grateful to hear your opinions on the damage to the outer surface, particularly is it necessary to repair ? From memory, when I dismantled the engine, nothing mates to this surface, does it (the engine was filthy, so I can't be sure!)?

Second question: Would you recommend disturbing the three grub screw oil gallery plugs (2 x 952075 at the front and rear of the block and a smaller one 952069 on the RH side of the block forward of the oil filter) ? They're stuck fast and the square holes feel like they're threatening to round off.

Thanks as always,

SL

A follow up after some more thinking about your problems.

Second question first. My recollection of the blanking plugs were that they were equipped with a recessed hex head (allen head) - at least on my B20E. Clean them out carefully and check. If they are allen head and you are trying to use a square plug drive that may explain why they are threatening to round off. As suggested by others, heat (a lot of it) can be your friend when removing recalcitrant bolts.

Something to consider. You don't have much to risk by attempting to remove the plugs. If you don't remove the plugs then oil gallery cleaning is left to the next person. If your plugs heads round out and you leave them in place then oil gallery cleaning is left to the next person - same outcome. If the engine has been sitting for a long time I think it is worth the effort to try and remove the plugs to clean out the galleries. Otherwise you are going to be flushing a lot of mineral spirits through the block in an effort to get them clean.

First question second. You are correct that nothing 'mates' to that surface. But now that it is not 11:30 pm (local time when I first posted) that is the rear thrust face for the crank. About the only thing that I can think of that could cause the damage is careless placement of the crankshaft during assembly. Almost like the edge of the thrust face on the crankshaft caught the thrust face on the bearing and gouged it. When you reassemble the engine make sure to check your crank to bearing thrust face clearances to make sure that there has been no damage / wear to the crankshaft thrust faces. You don't want the crankshaft walking back and forth during operation.

I am hoping that new bearings are a 'given' during this rebuild?

[mocambique-amazone]

Yes, like the others wrote:
The damage is on the bearing shell. This surface is to guide the crankshaft axially. If you go onto the clutch this part is stressed heavily.
It will be damaged by rough assembling.

And yes too: remove the core plugs.

Good luck, Kay