maestro to mg convertion

[big norm]

High Is anybody able to help, I have an mg zr with the prima engine that has the hydraulic buckets it has had several problems with valves not sealing, tight clearances, buckets jacking out etc. I have got the head off again coz of another missfire it's had another set of new buckets recently, now its got some bent valves and valve seat recession I am getting peed off with it now- ----- but I have somewhere an old meastro td engine and a few spare heads I think lurking in the depths of my workshop and I am sure the good old maestros had solid lifters n shims, the old shim it and forget it style, that went on and on and on , I believe the buckets are different diameter/sizes---- BUT will the whole head fit the zr block so that I can recon it, fit it and forget it !!! .
Any help would be gratefully received .

TA BIG NORM

[E_T_V]

High Is anybody able to help, I have an mg zr with the prima engine that has the hydraulic buckets it has had several problems with valves not sealing, tight clearances, buckets jacking out etc. I have got the head off again coz of another missfire it's had another set of new buckets recently, now its got some bent valves and valve seat recession I am getting peed off with it now- ----- but I have somewhere an old meastro td engine and a few spare heads I think lurking in the depths of my workshop and I am sure the good old maestros had solid lifters n shims, the old shim it and forget it style, that went on and on and on , I believe the buckets are different diameter/sizes---- BUT will the whole head fit the zr block so that I can recon it, fit it and forget it !!! .
Any help would be gratefully received .

TA BIG NORM

The ZR never had the prima engine fitted to it. It did have the L series fitted to it though which is the next evolution of rover diesel engine. The Prima is the engine in the maestro/montego TD.

The tappets are EXTREMELY reliable. Infact I've never heard of one going wrong unless the cambelt has broken in which case they get smashed to pieces.

Equally valve seat recession is also unheard of so far, it sounds like something has gone very wrong with this engine!.

The Prima and L series head are likely to be similar however as the fuel pump is driven from the gearbox side of the engine on the L series and the pulley side of the L series swapping them is unliklely to be simple if indeed possible.

What are the original problems you are experiencing?

[big norm]

Hi I was going by this quote from this site http://www.roverdiesel.co.uk/lseries.html

The L-Series engine commenced production in 1995 and was Rovers first in-house designed and manufactured direct injection diesel engine. It is derived from the established Perkins MDi Prima engine used in the Austin Montego, Austin Maestro, and LDV Sherpa van. The L series is extremely versatile and has been fitted in the Land Rover Freelander, Rover 200 Mk3, Rover 400 Mk2, Rover 600, and European versions of the Honda Accord and Honda Civic. A development of the L series engine (The G-Series) featuring a modern common-rail fuel injection system was underway when MG-Rover ceased production, but the company's closure prevented it from being fully developed and released.


There are several forms of this engine.
The first is a non intercooled, mechanically controlled fuel injection system. This version is available in Rover 200 and Rover 400 models and the model designation ends in "D", i.e. SD, SLD etc., etc.
The second is intercooled and has an electronically controlled fuel injection system. This version is available in Rover 200, Rover 400 and Rover 600 models. The model designation ends in "Di", i.e. SDi, SLDi etc., etc.
The last and most recent engine is intercooled and also has an electronically controlled injection system which is slightly more advanced and produces more torque than earlier models as earlier intercooled models and either more or less power depending on the ECU map installed. This is the version that is used in the Rover 25, Rover 45, MG ZR, and MG ZS.

I am not argueing with you but my head/engine man ( of vast experience used to do the machining for the mg dealers etc and still does L/rover) at one time was doing 10-15 k series heads a WEEK !!!, says it is quite a common fault with the mg heads to recess valves and close up the clearances, but I am not claiming to be an expert on the newer engines and I appreiciate any help

Best Regards Norm

[E_T_V]

I wrote that text!

I might need to reword it to make it clearer.

O series petrol was turned into Prima diesel
Prima diesel was turned into L series diesel.

K series headgasket problems are incredibly common. L series ones aren't.
Valve seats can move on the T series if they are overheated a lot, but I've never heard of the L series or prima doing this (probably due to lower combustion temps in a derv).

What are the symptoms you are getting. That is probably a better place to start, as head problems are extremely uncommon.

[big norm]

Thanks for this, its a friends they have owned this car from brand new, problem now is the head gasket has gone though there is no obvious cause appart from the pressure cap was not a pressure cap it was a free to air breather !! it has not got hot just pushes the water out with the gasses, they have had to have the crank ground 12 mths ago due to lack of oil pressure though I was not involved in that, before that they had missfire probs it would start up fine and as soon as it got slightly warm it would go onto 3 and sometimes 2 they took it to the mg dealers who had it for a week and couldnt find a fault, I had a quick look to try and help and suspected the buckets, as per the old vauxhall motors (I had one astra that had 300k on it, same prob missing, turned out it had 120psi oil press!! dropped the oil pressure to 70 ran fine, still had a bit of valve reccesion though ) they took it to mg again and told them of my idea mg put a set of buckets in and it was on 4 ish again, but said they thought it had gone through water and bent a rod , it struggled round for a few months but had very low power,that is when I had a look and found the cat was blocked and the maf sensor was u.s. at the same time I plated out the egr and she then had a reasonable amount of power again but still not 100% right but it got her to the shops and back, good enough he said !! So I pulled the head for a look did a parafin test in the ports, and --- there was the slightly bent inlets no.1 def no.2 just ever so slight, so then I suspected the buckets jacking out again, though couldnt see any clippin marks on the pistons checked the piston deck hights all ok,so no bent rods,Took it
to Eric the head man we washed it and checked it,some of the seats are not exactlly in line with the worn guides etc so we thought about a different head and I came up with the idea of the maestro heads,I had two of them as service vans thrashed to death and still came back for more
And thats the story so far
THANKS HOPE YOUR STILL AWAKE !!!! Norm

[E_T_V]

Ok a few possible things to try and rule out

Low oil pressure has caused engine to overheat massively?
This will move the valve seats in the head and also cause it to warp leading to the gasket blowing.
It wouldn't cause it to misfire though

Hydraulic lock from water ingestion
This would cause the gasket to blow and possibly bend a rod. The pistons should protrude fom the block at TDC so if they are below this then the rods are bent. Bent rods give low compression and so it'll misfire which may go away when the engine gets warm.

Cambelt slipped/broken
This would cause pistons to hit valves and destroy the tappets and could bend the rods. It can also destroy the headgasket causing overheating and waterloss problems. Belt changes are very frequent on the MG dervs and s often get missed.

The L series valves are vertical so even if they hit the piston they rarely bend. What often happens is that they destroy the hydraulic tappets or break the camshaft. I've known people who have snapped timing belts simply replace the buckets and have a perfectly normal car.

If the expansion tank cap doesn't hold pressure then the coolant will boil in use and you'll eventually overheat the engine even if there is no other engine fault present. If the headgasket has blown then it'll also force water out of the expansion cap.

The usual fault with the L series is wire chafing so carefully check the wire from number 1 injector and the wiring around the pump area.

I have literally never heard of lifter problems that haven't been caused by the pistons hitting the valves so I'd be double checking the cam timing too.

[big norm]

Hi again
When I stripped it there was no evidence of the engine having been over hot, I think the oil pump poss caused the low oil pressure and it to run its crank brgs, as long as the pump gave 5-10psi the light would have been out,---- happy motoring---- till you get that grumbly rumble!! the pump was replaced at the same time as the grind.
The odd thing was prior to the crank eppisode was this warm missfire, start it cold, it was on all 4 then 3-5 min of idling it would drop onto 3, could not tell which cylinder though, tried slacking injector test but the engine died probably due to pump pressure loss, mg did a compression check, all fine ( so they said, though a diesels at 19-1when cold is not quite as black n white as a petrol when cold ) then it would on occasionally drop onto 2 as it got warmer, similar to the petrol 2ltr T series with the valve carbon problem holding the valves off, but this was more severe, obviously, because its a diesel and it needs the compression to fire at all,
The new buckets sorted it and as I said I have checked the pistons/deck height, and there are no bent rods, so why did new buckets sort it? what was causing compression loss when warm, unless it was the oil press too high for the buckets and not allowing the oil back out as the valve expanded, maybe this high oil pressure caused the pump or relief valve spring to fail ?
When I stripped the head off the bent valve was not badly bent, only evident when cleaned off and looked at closely on the valve seating area, doing the parafin in the port test , took six hours for that port to empty . All the valve springs seem good and equal the only indication of the low compression was on cold start up a slight variation in cranking speed as the bad cyl went over tdc ,and the slight lack of power when running and also that would not have caused the massive compression loss that was evident b4 the crank grind, as the engine warmed also the fact that MG doing the bucket job sorted out the cold to warm missfire, back onto 4cyl, as far as the bent valve would allow, but why was the valve bent in the first place, as I stated earlier there are no valve clipping marks on the piston heads Valve timing seemed ok but it looked like MG had moved the pump timing on the pump end of the cam vernier pulley, retarding it a fair amount which would also give it a lack of power.
It is looking more like an exchange head is going to be the way forward because this head is going to need seats, valves, guides, buckets skim etc etc .
Thanks for your imput to this
Norm

[big norm]

Hi
Me again I going down to welshpool sat morn so if I dont reply immediately I am not being rude
Thanks again Norm

[E_T_V]

Don't worry I'm just off to an MG car show in a mo so I'll need to reply when I get back too. I'll have a think but certainly a second hand or recon head seems the best way forward. The only other concern would be excessive ring wear or piston wear if the oil pressure had been low for a long period or even a cracked/melted piston due to insufficuent oil cooling to the piston crown, although that should be obvious with the head off.

Was the right headgasket fitted as there are 3 sizes of gasket, indicated by the number of holes in the gasket?

If the piston/valve contact was only a one off then the marks will quickly soot up and be hard to spot.

If the fuel pump timing is wrong then the ECU light will illuminate. The pump timing is altered dynamically when the engine is running anyway so if it is wrong the engine just won't start.

[big norm]

Hi I am back from welshpool but tommorow I am picking up a complete recon head with cam n buckets etc, I think this is the best way forward with time, head warranty, etc all concidered. As far as the timing is conserned I could see where the bolts holding the vernier pulley had been from one end of the slots to the other, but they where tight, and it look as if it had NOT been run slack, so from that I would think somebody has been in there playing, from the quick look I had at it it looked as if it was fully retarded because I think it works the opposite, to the way it acctually looks, if you follow my thinking, maybe they thought by advancing the pump up it would maybe make it go a little better but it would not compensate for a bent valve !! but by retarding it, it made a bad job even worse. Poss thats why the cat n egr where sooted up etc . found out yesterday it's also had a new turbo !!!!! fitted a few months ago (trying to make it go a little better?)
I think it would have been cheaper for him to buy a roller----- and I don't mean of the royce variety, I mean of the road type and rolled the fking thing flat so it would have been easier to take to the scrappy!!!! HA