PART 1 - The Investigation and Stripdown



Well my 75 Clutch gave up last saturday so the Cabriolet was then nominated to
be the daily driver, it lasted 2 days before I spotted this.









Upon closer inspection under the bonnet I found a rather empty bottle.












After consulting 'The Almighty Dist' I ventured under the car and found this.








So a tinker day was setup on Thursday with mtecstevo to replace the water
pump but since this requires playing with the cam-belt we decided that it
would be wise to replace it as I have no idea when it was replaced last or if
it has at all.

Before stripping fully we did a compression test just in case the head
gasket had been compromised, the results were as follows.

1- 15
2- 14.5
3- 13.5
4- 13.5

Not the worst results, a bit uneven but within tolerance.

As we started popping bits off the engine we found the dizzy cap points were
quite worn out so that ended up going on the list with the belt.











The rotor arm was also past it and a couple of the spark plugs were also
worn out so I ordered a full ignition system, Plugs, Leads, Dizzy & Rotor.

The water pump looks like it has been leaking for a while.

Stevo then summed up the damage MAD MAX 2 style *laughs*.



LINK: https://www.youtube.com/watch?v=ZYr5TDfHxjc





Since I had a headgasket and bolt set already he suggested checking out
the current one since we were doing the cambelt and waterpump so off
with the head it was.










Now we were at this stage I decided to take the plunge and blow the dust
off these that I have had lying around for a few years now.









They are MG TF 135 Cams, they were upgraded cams with a higher lift
and fitted to the non-VVC 1.8 but can't see why they won't improve the
1.6 in the Cabby, shame it can't be remapped or chipped as it is MEMS
1.9, I do have an SuperChips ICON Race Box but there is no support
offered for it but I may look into it again as I also have a VVC inlet
manifold lying around so that will be fitted too, it is off a 1.8 but the
ports on the 1.6 are the same, this is becoming more than a waterpump
repair, its an engine overhaul and upgrade.

For anyone interested the lift on the 1.6 standard cams is: 38.8mm
The lift on the MG TF 135 cams is: 39.5

Combined with the inlet manifold it should get a good gain.

Anyway, on with the removal of the cylinder head, the cam carrier got a
light cleanup, the oil was decent and the engine looked well maintained.









The headgasket looked like the original, if so its laster 90,000 miles but
it is on its way out, probably a result of the waterpump, looks like its on
about 75% integrity.













The head and block surfaces looked ok, some staining, light corrosion and
pitting but a rub down with some 1200 grit wet and dry on a wood block
with a spray of WD40 brought them up a treat and we now have a nice
fresh surface for the new MLS gasket to sit on.












This is as far as we could go until the shopping list arrives, on order we
have the following, if anyone would like the links I will get them as it was
a bargain, £107 for the lot.

Cambelt Kit - GATES
Waterpump - Comline
Sparkplugs - NGK Platinum
HT Leads - HighVolt
Rotor Arm - Intermotor
Dizzy Cap - Intermotor


Keep an eye out for Part 2, the rebuild, weather permitting we will be
cracking on with this on Monday or Tuesday.

I'm interested in this HG job, as mine (my first) went pear-shaped despite? because? of my being paranoid about making some non-obvious but elementary blunder. This had made me read up about pitfalls perhaps more than was wise.

I can see on your head photos that the old fire rings have excavated shallow indentations on the sealing surface, and there seems to be corrosion pitting from tired coolant. Could you perhaps show us the result after the wet and dry treatment, for completeness? Mine was actually less tired than yours, but my paranoia made me get it skimmed. I wasn't entirely pleased with the surface finish it received, but they were professionals after all. Google Streetview even showed a R8 Cabby outside their door! If yours succeeds without a skim, I'm wondering if I shouldn't have bothered! Particularly as the new gasket leaked combustion gases into the coolant.

I'm considering re-doing the job with a saver shim, combined with elastomer gasket, as my project isn't worth the hassle of changing the oil rail to suit a MLS gasket. It would help my thinking if you could show us a pic of the shim from your MLS kit overlaid on the head, please?

You only need to skim really if you know there has been potential heat damage from overheating the engine.

as long as its clean and you know it never overheated, you should be fine.

Which gasket are you using?

Elastomer
MLS or the N series one

I've just done my kettle err sorry 1.8T headgasket. Also fitted the upgraded oil rail too and 10.9 bolts.

Gasket choice is partly determined by the liner heights. Check them to make sure they are ok (if its not overheated they probably will be fine). But you should check anyway.

I'm not so sure that I would put OAT in it?

I know it was originally specced for the MGF but a knowledgeable gentleman on here reckons all R8's have a copper heater matrix?

I investigated the coolant issue and had the following response from Practical Classic's Mag' to my query.

" OAT antifreeze is not suitable broadly for any vehicle prior to 1995/6. It destroys all copper based alloys. There are two differing families of OAT chemicals and one of them also attacks the elastomer's found in plastics used in gaskets seals and washers."


Regarding those high lift and I assume longer duration cams , will the ECU adjust the fuel injection period to allow for the larger charge of air in the cylinder? A weak mixture will make the head run hotter. I expect the valve timing will change too?

HEAD CLEANING/SKIM - The pics posted are of the head after we did the light sand on it, the surface is glass smooth, there was no overheating issue so should be fine, not as if these engine are not cheap to repair though, I have a spare 1.4 head in the garage if it all goes tits up.

COOLANT - Well this Cabby is a 1997 and its basically the same gear as fitted to the 25 which runs OAT, can't see it being much of an issue though.

GASKET - Its just a generic MLS from 'Gaskets for Classics' pal, regardless its going to be better than what was removed *laughs*.


UPDATE COMING TONIGHT !

ROVER-25X wrote:COOLANT - Well this Cabby is a 1997 and its basically the same gear as fitted to the 25 which runs OAT, can't see it being much of an issue though.

*lightbulb* A question about pollen filters recently had me looking through heater parts diagrams on Rimmer's site. As far as the 200 goes, the R8 heater and core did not get carried forward to the R3. With the R3, I believe OAT compatibility arrived, its heater core contributing to this. Further, the R3 heater is part and parcel of the R3 Bubble dash. So a late-build R8 factory fitted with a Bubble dash would very likely have the same OAT compatibility as a contemporary build R3.

ROVER-25X wrote:GASKET - Its just a generic MLS from 'Gaskets for Classics'

Are you going to use a saver shim?

ROVER-25X wrote:
GASKET - Its just a generic MLS from 'Gaskets for Classics' pal, regardless its going to be better than what was removed *laughs*.


UPDATE COMING TONIGHT !

Not necessarily.

If liners are low or uneven height then the elastomer gasket usually lasts better than the MLS one.

The MLS one is only better if the liners are even and proud (0.1mm aim). Otherwise you end up with a repeat failure like I've just had on my ZT. (because the muppets didn't check the liner heights).

Hoping it should be ok mate as the gasket didn't actually fail, just the waterpump and that was caught,
the oil and coolant were still separated in there respective engine channels.