Some easy engine questions for you...

[Varsas]

Hi.

I am replacing the bearings (main and big end) on my 3MB 2.25 diesel engine.

After replacing the main bearings the engine still span fairly easily (up until now I have been doing this with a set of stilsons on the front nut, it's not diffficult with the glow plugs out to remove the compression) however with the new big end bearings in the engine is quite stiff, I can only just turn it with the stilsons. I put 010 oversize bearings in as the writing on the crank said that's what to use. I assume it's normal for the engine to be a bit tight after new bearings?

Also does anyone know what size the front nut is? Once the engine is in the car and we are trying to line up the gearbox we are going to need to be able to spin the engine easily, so I'd like to get a socket for it. I have a 1 1/2 inch socket and that's too small, I assume it's 1 3/4 inch maybe? I did try measuring it but it's difficult as the starting handle (?) knurled end gets in the way.

Cheers.

[Rich_P]

I wouldn't have expected it to be stiff with new bearings? When I changed the big end bearings and inspected the main bearings on my petrol engine, it was just as easy to turn over by hand afterwards as it was prior to work. Are you sure you haven't got a bearing pinched or slightly off from where it should be seated?

If it helps any, it was possible to turn my petrol engine over by just turning the front pulley by hand. Obviously the spark plugs were out so no compression, but the same should be for your engine with the injector or/and glow plugs, right?

[RustyNissanPrairie]

possibly dirt trapped under a bearing shell, or to be on the safe side use some plastigauge on the bearings/crank journals

[Varsas]

hmm, not good. I'll remove and re-fit them all then. My fear is that the bearings are too big...

[Les Henson]

There should be no noticeable additional stiffness after replacing the bearing shells. I've had 'odd shells' once before and they pretty-much locked the crank up when the cap was torqued down. If you've turned the crank and it's stiff, then the new shell/s will be marked and can be identified.

Rule of thumb is replace a pair of shells, turn the crank to check it's ok, then another pair and check again, and so-on.

Les.

[georgethedog]

Hi there

I realise this may be a bit obvious but why not use a starting handle, a lot less hassle than a pair of stilsons and a lot cheaper than a deep series 1" and whatever socket,

also, if its too tight for a starting handle its too tight.

Did you have the crank polished before fitting the new shells, I ask this as the guys who polish the crank will measure it and and supply shells to match.

My crank was stamped 0.010 u/s but the shells said standard, whats that about, confused me but it is 45 years old and its probably had some odd owners/mechanics

hope this is'nt a red herring, oh yes Turner Engineering are very helpful, not as cheap as paddocks but you only need to buy it once and its fits straight away

Cheers

[secondjeremy]

If the bearings are tight there's a risk of severe damage on startup - and at other times. I've even heard of shells rotating.

You shouldn't need to turn the engine much when fitting it if you get the clutch aligned properly - and if you don't spinning won't help anyway.

[Varsas]

Hi.

Thanks for the replies.

Yes, Turner engineering is where I have been getting the bearings from, but I haven't actually spoken to them.

Yes, I did think about a starting handle but I couldn't get hold of one quickly. We have bodged up a tool with an old breaker bar that does the job now.

I had another look at all this last night.

With 010 oversize bearings on piston 1 and 4 the engine spins fine.

With 010 bearings in piston 2 it does still turn, it's a bit tight but after spinning the engine 5 turns and then removing the bearings there are no marks on the bearings or the crank, and it did get easier as I span it. (yes, we have been oiling the bores!)

With 010 bearings on piston 3, even not torqued up (just nipped finger tight) the engine will only *just* spin 1/4 turn, I can't put any more force on it as it's in danger of coming off the engine stand. When removed the bearings were scored and there were bits of bearing on the crank...obviously not good(!) thankfully the crank still seems OK, yes starting the car with the bearings like that would have been disastrous. I'm very glad I asked now.

So..I have ordered a set of standard bearings and am going to try a set of standard size on piston 3 and hopefully that will be OK, I would really like to avoid removing the crank.

Interestingly there are no markings on the old bearings to indicate that they are oversize, but I guess that doesn't mean much!

Oh..and see the pic for the result of last nights work! I know most of you won't be very impressed but it's my first time doing anything like this and I am quite proud!

[Les Henson]

If Turners supplied the bearing shells, then it's highly unlikly they will be the problem.

What was the reason for doing the bearings, general rebuild/repair?

Les.

[Phil Hancock]

Just a thought but the connecting rod big end cap on the problem piston is a match for the rod and the correct way round?

[secondjeremy]

Sometimes the bearing shells have the part number on them - this would give the size. (If you haven't the part book use one of the on-line shops or possibly the Bearmach part finder (download from their site - handy thing as it gives all the numbers for a part))

[secondjeremy]

Sometimes the bearing shells have the part number on them - this would give the size. (If you haven't the part book use one of the on-line shops or possibly the Bearmach part finder (download from their site - handy thing as it gives all the numbers for a part))

[Briarston]

Can't you "mike" the jounals? Even careful use of calipers should allow you to compare

the "tight" journal size with a good one. I would think it unlikely that a machine shop would only grind some of the journals.

Not necessarily on an LR. engine, but I have seen several that have been bodged up by

filing the bearing caps to tighten them up.

You could try temporarily fitting a cap from one of the "free" rods to see what happens.

Yes, I know that the rods and caps are bored when bolted up and so should be kept together.

[Rich_P]

The big end bolts are aligned correctly and pulling all the way through to their seated positions aren't they?

[Varsas]

Hi.

I am changing the bearings because the ones that came out were badly worn, you could see the copper in a few places on all of them. Since the engine is outside the car anyway I thought it'd be straightforward to change them...

I have been careful to keep the end caps with the piston they were removed from, and the correct way round. Yes, the bolts are seated correctly (I did very nearly make that mistake!) although oddly the bolts for that cap do protrude further then the rest, you can see much more thread then the other bolts.

I have checked the part numbers. The oversize ones I put on have the same part number as the ones that came off.

Hopefully I'll be able to have another look tonight, my standard bearings have arrived so I'll try them.

Just to double check (I'm just putting them back as I found them, which doesn't mean they are right) which way round do the end caps go? I am putting the end caps on so that the tab which prevents the bearing from slipping is at the bottom, opposite to the tab which is on the piston side. (I am looking up at the engine from underneath, with piston number 1 to the right). Should the tabs meet or be on opposite sides?

[Phil Hancock]

Should the tabs meet or be on opposite sides?

Opposite sides of the engine.

[Briarston]

Opposite sides of the engine.

Whilst admitting that I am not over familiar with the internals of these older LR

engines, and in no way am I intending to contradict those who are, having worked on

many engines since the 1960's, I have never come across one where the bearing caps -

big ends and mains - have not been fitted "peg to peg".

Apologies if I am wrong in this case, just adding a caution.

[Varsas]

Well Briarston I actually hope you are correct. I will take the 'old' engine apart and find out how that is.

I did have a look last night. I fitted standard size bearings to the 'problem' cap and for a while I thought it was fixed, the engine was a bit tight but would at least spin with the bolts torqued up. This is the first time this has been possible.

I then bolted the oil pump in place and went to spin the engine again (to make sure it was still OK) and it was stuck. Removed the pump, still stuck.

I could only free it by loosening the end cap bolts. I then put plenty of oil down the glow plug holes and span the engine a good 10 times before retorquing the bolts...but once again after leaving it for 20minutes or so the engine wouldn't budge. I am coating the bearings in oil before they are fitted.

So yes, that's where I am at the moment.

I am also stuck because the 'old' engine must be a metric one and the 'new' one imperial so I need clutch housing bolts, engine mounting bolts and an alternator bracket before I can continue...

[Varsas]

Just a quick update.

I spoke to Turner engineering, who were very helpful.

The tabs should be together, so my bearing caps are upside down although that may have been done when they were machined.

I also now have the dimensions of a standard crank, so I can measure mine to see what size my journals actually are, oversize bearings should have the size on them, which mine didn't suggesting they were standard.

I am also going to make sure by caps are in the right order, apparently people do mix them up...

[Briarston]

Just a quick update.

I spoke to Turner engineering, who were very helpful.

The tabs should be together, so my bearing caps are upside down although that may have been done when they were machined.

I also now have the dimensions of a standard crank, so I can measure mine to see what size my journals actually are, oversize bearings should have the size on them, which mine didn't suggesting they were standard.

I am also going to make sure by caps are in the right order, apparently people do mix them up...

If the caps are on the opposite way to how they should be, this may well be the problem.

The big end bore is not necessarily exactly centred between the studs, and thus could be causing a slight offset of the shells. Could be enough to lock up the bearing, in the way you have stated.

Hope you can get it sorted. A nuisance, but better found now, rather than when refitted!