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MG MGB Technical - V8 Engine Problems

I have just taken the plunge and purchased a 1974 factory V8 but it has been standing for the last 25 years.
The engine had been run approximately 5 years ago.
I have got the car home and removed the spark plugs the engine only turns roughly a quarter of a turn until it stops it will then turn back a quarter of a turn.
Thinking it was the hydraulic tappets locked up I removed both rocker shafts but still the same. Any ideas would be grateful as my next step would be to remove the manifolds and then the heads.
a goldup

That is a head off for starters. you could do horrible damage by trying to start it after all that time at rest.
Sandy
SANDY SANDERS

Take no chances! An engine that has been sitting that long should be completely torn down and every component examined. At the least. the seals and gaskets are due for replacement.
Stephen Strange

What colour are the components under the rocker covers?

Silver - good, low mileage or well looked after
Light brown - higher mileage but still good
Dark brown - high mileage, probably in need of at least camshaft replacement.
Black - likely to need a rebuild
Black and crusty - pretty well dead!

The turning issue is unlikely to be the top end - could be a transmission issue or a bottom end problem. As Steve says, time to pull the engine and strip it.
Chris at Octarine Services

Thanks for all your posts.
The starter solonoid is dead so no supprise there.
I have only tried to turn the engine by hand but have not forced it. The rockers are covered in a black thick but fairly dry oily muck but the flame traps where solid.
I cant understand why the engine will only turn a quarter of a turn as it was a runner when it was put away. I am not sure taking the heads off will show me what is wrong unless there are some stuck valves. I am toying with taking off the front cover and having a look at the timing chain. I cant think of what else would stop it turning. I don't realy have the equipment to rip the whole engine out.
Does the engine come out without the gear box.
May be I should quit now and send it to the brakers before I spend a fortune, shame realy as it is a factory V8 and the body was restored three years before it was laid up.



a goldup

More Pics


a goldup

If it's really that bad, I'll take it off your hands ;o)
Dave O'Neill 2

Make me an offer it has the genuine chrome alloy wheels.
a goldup

Yes, you should pull the engine and transmission as a single unit. Block the front wheels and put the rear axle up on axle stands so that it will be easier to maneuver the engine/transmission package. Removing the radiator and its diaphragm makes getting it out easier, too.
Stephen Strange

Sounds like the engine was well overdue for a rebuild before it was laid up.

Don't scrap it - either budget for a recon engine or sell the car on to someone who can fix it.
Chris at Octarine Services

Hi A Goldup,
I have been looking for a V8 project for some time now. Where is the car, is the rest of the body as good as your second photo. In fact I've lots of questions for you!
Cliff R
C I Robinson

Hi Cliff you can email me on logic.mobiles@virgin.net.
I can send more photos but please only sensible offers as this car is a factory V8.Car is in Kent.


a goldup

Hi A.Goldup

Cannot understand why you would even consider scrapping the V8. Fair Dinkum!
Why not source a used short motor and transfer your ancilleries (if in usable condition). Surely this would not be too expensive. I have just been through this process myself with great success.

Regards

Graham
G J HOYLE

A Goldup
With respect any offer from an enthusiast would be superior to your earlier suggestion that you might send it to a breaker. Please don't even contemplate such a course of action - there were far too few of these fabulous cars made and all efforts need be made to ensure that those we are left with are preserved.
Peter Malkin

"I am not sure taking the heads off will show me what is wrong unless there are some stuck valves."

Just taking the rocker covers off will show that.
PaulH Solihull

Next update on the V8.
Have taken of the inlet manifold and the waterpump. Yesterday I sprayed wd40 into the bores, today the engine turnes over. Next off with the heads but I cant find the nuts or bolts to slacken off the engine mountings they must be well hidden. I have ordered a V8 workshop manual but it wont be here for a few days and I want to get stuck in.Any tips ?
a goldup

The engine mounts have a top and a bottom of course. The bottom is a single stud going through a chassis bracket and so accessed from underneath. These are real pigs, needing a 16-point ring spanner that has to be turned over twice for each flat! That's the easy side, the difficult side has to have the steering rack completely removed first!! I've done some that were so rusted, even with copious applications of Plus Gas, that needed a rope on the spanner and someone pulling on it from the appropriate end of the car to get enough force on it while I lay underneath and turned it over for each half flat. Even that only undid one of them, the other was so tight the bottom of the mount was twisting and springing back, so I had to drill through its base plate and the chassis bracket and put a pin through it (actually the drill broke and did that part of the job) to stop it twisting. I simply wouldn't bother again, just chisel the rubber off the base plate to remove the engine, then grind the base-plate off the chassis bracket and use new mounts.

The upper nuts and bolts, two on each mount attaching them to the block brackets, are attacked from above. Can't remember any issues with those, I've changed mounts a couple of times with the engine in-situ. I've also removed the block brackets with the engine in-situ because they were fitted to the wrong sides, and that was a real challenge!!!

The mounts are 'handed' in that the stud on the bottom is offset from the centre, and this must go in the lower of the two possible positions. Under the chassis bracket there is a square location plate with an offset hole that goes on the mount stud as well as the lock-washer and nut. This location plate must also be fitted so that the hole is in the lower of the two possible positions. There will also probably be one or more spacers between the mounts and the chassis brackets or the block brackets, these are all to ensure correct engine location. If the mount studs sit in the bottom of the slots in the chassis brackets on either side you need more spacers, otherwise the rubber mounts will be in shear and tension and will fail. If you can't get the location plate on correctly orientated, and tapping the bottom plate of the mount down doesn't help, then you need less spacers. The mounts studs must be near but not at the bottom of the slots in the chassis brackets to ensure the rubber is only in compression.

Even though the chassis brackets are slotted you probably won't be able to lift the engine straight out and drop it back in with the mounts undone from the chassis brackets but still attached to the engine, but instead tilt it slightly to get the first out/in, then tilt it the other way to get the second one out/in.

If the nuts are free on the bottom studs it's easier to remove the upper nuts and bolts then you can spin the mount off the nut. Ditto for replacement, but you will need to fit the upper bolts and nuts and tighten those before determining what spacers are required.
PaulH Solihull

Thanks Paul.
Looks as if you want to do one thing on this car you have to do four others first.
Do you know if the engine can come out leaving the gearbox in the car?
a goldup

Definitely, and that is the way I would do it even if removing the gearbox as well, given the lift I have available. I've not done it on the V8 (yet), but on a 4-cylinder the process was:

Remove the upper bell-housing bolts first. With the engine mounts undone lift the engine and gearbox so the bell-housing is just short of touching the top of the tunnel. Jack under the bell-housing until it just starts to move upwards a bit more. Remove the lower bellhousing bolts then you should be able to pull the engine forward off the input shaft. That's after doing everything else needed for engine removal of course!
PaulH Solihull

Four hours to get the two nuts undone on the engine mountings. Rack came out in 10 minutes.
Heads now off but engine still does not want to turn over all the way. All piston are moving, next out with the block.
a goldup

FWIW removing the inlet manifold and its big tin gasket will allow you see down into the innards.
PaulH Solihull

Have to own up hear to a bit of a mistake.
Found the car had been put into gear when the seats where removed. Engine turns over as it should.
Block coming out this weekend.
a goldup

Well, ain't that a kick in the head. But, after 25 years, it's probably best that you pull it anyway. Nice that you found out it isn't seized.

Charley
C R Huff

Kudos for admitting it!
PaulH Solihull

I have cleaned off the top of the pistons but the only markings I can see is an capital A.
Does anybody know if this is a marking for a standard sized piston.
a goldup

Hi,

Stirring around in the dust of my memory is a thought that the A is a grading mark, from the factory. The pistons were graded, by weight I think, so that when an engine was assembled there was a reasonable balance, by using pistons of the same grade. Therefore I presume that you have original pistons.

Herb
Herb Adler

Block came out today.
Found the clutch stuck to the flywheel and cover this is probably why the engine would not turn when I first got the car, clutch looks in good condition as it was renewed 20 thousand miles before the car was put into storage.
The bores don’t look to worn hopefully I will get away with a set of rings and a hone.
a goldup

Only if it was in gear and you had the clutch down while trying to turn it. If the car is *not* in gear the clutch and gearbox input shaft turns freely with the engine even if the clutch is stuck.

20k? I wouldn't put that back in, personally.
PaulH Solihull

I agree with Paul. I would change the clutch, press. plate, drive plate & thrust bearing while the engine & gearbox is out. You've already done the worst part. You might get lucky with the old parts,but it could also be a case of false economy. Barrie E
B Egerton

Starting to rip the engine apar,removed the camshaft it has dark stains on the lobes is this normal or do I need to add this to my ever growing shopping list. The followers seem to have different wear marks. Some had a circle in the middle and others have an even dish. Crank out at the weekend wonder what I will find ??
a goldup

Once you get the engine stripped down, I think you are going to have to take the parts to a competent engine person to have them inspected. I don't think any reliable inspection can be accomplished from just a description.

Charley
C R Huff

I'd advise changing the cam and followers as a matter of course. The followers should have an even dish, if anything, an elongated wear mark indicates they have not been rotating as they should, which could have affected the cam, which is difficult to check for wear. FWIW I changed my cam and followers in an attempt to cure a hot rattle and found the followers had negligible wear, only about 1-2 thou dishing, the bores also clearly showed the honing marks over most of their surfaces, and the engine had done 80-100k since the last rebuild. Incidentally the bearings were still just in spec for *new* bearings and have the same mileage, and it has now done over 200k on the original unreground crankshaft. The interior was a light bronze colour, a testament to oil changes at 3k and use of a pre-change flush.

When fitting new followers you may hear about 'pre-load', which is the amount of clearance when the followers are empty of oil. One source quotes 20 to 60 thou on their website, I found mine were 110-120 on one side and 40-110 on the other! Spoke to the website owners and they said "you wouldn't want to go as low as 20 and 120 should be fine". The MGOC and Clive Wheatley both said that unless the engine is highly modified those figures are fine, the whole point of hydraulic tappets is to cope with variations such as this.
PaulH Solihull

Just to give you all an update on the engine.
Took all the engine parts to the machine shop last week.
Bores have 5 thou taper so they recommend a light hone and new rings.
Pistons have no wear at all.
Heads are flat but need attention to the large waterways. They will be welded and then machined.
Two exhaust guides have excessive wear but all valves within tolerance. Requires two guides.
Crank has no wear so a polish and new bearings.
Front cam bearing has excessive wear so new cam kit and bearings required.
Cost of repairs 250

Not too bad for engine that has covered 78k and has been standing for 25 years.
Got all the parts from a Landrover specialist as he had better purchasing power with the engine parts suppliers than any of the mg specialists that I use.
Got all the parts below for under 300 delivered.
Head set with composite head and inlet gaskets and rubber valve cover gaskets supplied in addition to the metal ones in the sets
Camshaft, followers, chain, both gear wheels and hydraulic lifters.
Cam bearings, big ends and mains.
Oil pump gears.
Piston rings x 8.

Does anybody recommend running in oil of just a good quality 20/50 and then change at 500 miles.
a goldup

I changed mine after the first 20 min running (to bed the cam) then at 500 and then a regular, every 3000 miles
MGBV81

When I had my engine done the machinist said use any cheap 20/50 oil as the galleries in the V8 are big enough. He said run til warm then dump the oil and filter. Gets all the machining junk out. I then changed at 500 and now just once a year which is about 5000
A J Ogilvie

It's said to use an 'older' spec of oil for running in as modern oils (even if you can get 20W/50 in the UK) won't bed the rings in. Some recommend straight Castrol 30, but Castrol XL 20W/50 to API SE/CC should be OK, anything earlier than SJ but you will have to go for a specialist for it.

Unfortunately any junk that hasn't been flushed out *before* you reassemble the engine is likely to score some of the main bearings, which is why the galleries should ideally be flushed out with oil and not just air. My V8 has done getting on for 100k since any work, all the bearings are just at or inside the specs for *new* bearings, and the bores still show honing marks. The big-end shells and journals show a mirror finish, but the front main (and to a lesser extend those further back) do show some marking.
PaulH Solihull

Just to let you know the outcome she fired up today for the first time in 25 years.
Just need some new manifolds and a front to rear fuel pipe. More expence !!!
a goldup

Whatever you do DON'T leave WD 40 in the bores for more than 4 weeks, after that time it degrades and becomes hygroscopic, i.e. it attracts moisture! Engines have been rusted solid in storage by squirting WD as a preservative, use some 3 in 1 or sea 30 oil.
Allan Reeling

Being an avid V8 owner well done to all of you, a really informative thread
B Clayton

Hi B Clayton from kent with a V8, where are you in kent. I am in Maidstone and now have two factory V8s.
a goldup

This thread was discussed between 16/08/2010 and 09/11/2010

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