The Triumph Dolomite Club - Discussion Forum

Hi All,

Not everything going entirely to plan with XLK 467S at the moment. Sprint engine experts advice needed! When I purchased the car I was shown a video were the owner had the car running for a few seconds from an external fuel source. I have only had the engine running a couple of minutes myself since in order to move the car, it has never ran well and was shaking on the engine mounts when running and idled very low at around 500rpm. Today I did a compression test and found the following:

Cylinder 1: 125PSI
Cylinder 2: 1PSI (Yes 1, like nothing)
Cylinder 3: 135PSI
Cylinder 4: 145PSI (Yay I have one 'good' cylinder!)

When replacing the plugs last year, Cylinder 2 plug snapped in the head (this should have been my warning that things were far from good).

Anyway today I grew tired of the guessing games so whipped the head off to take a look. What a mess (I almost cried). Engine work to this extent really frightens me, due to its very precise tolerances etc. With my minis I would just throw a £100 good second hand engine in and be done with it inside a weekend, I fear this is not an option with the dolly though

Anyway I will let the pictures do the talking.













My working theory now, is that some point fairly soon after the last MOT in November 1996 the head gasket failed on cylinder 2, letting coolant into the cylinder (weirdly I can’t see coolant mixing with the Oil), the car was then laid up from that point until my purchase in August 2021. Unfortunately all that coolant has caused serve corrosion to the piston and the cylinder head. The only saving grace looks to be the piston was at the top of its stroke so the cylinder wall is not mega corroded. There is scoring, but non that I can feel with my nail (it don't look fab though), the other cylinders look fine, with light honing marks visible. The engine has 79k miles on it if history/speedo to be believed. Does this diagnosis sound plausible?

I cleaned up one of the pistons and could see 0202L> stamped on it? Is this standard size/original?

Im at a bit of a loss, I was hoping to re-commission and start enjoying the car this summer! this has thrown a massive spanner in the works. Having looked up prices of pistons etc tonight, I reckon this is going to be prohibitively expensive to rebuild! I do have a very good engineering firm around the corner, however I can see this getting very expensive very quickly.

I did have the mad idea that perhaps I could find a used good piston (does anyone have a good used sprint piston on here?), and somehow fit this to the engine while it is still in the car via the sump? is this even remotely a possibility? I appreciate this engine will never be very good that way, but may have more compression than 1psi on cylinder 2!

I have a used cylinder head on its way that I will get the local engineering place to go through and check for me (With perhaps the lightest of skims if necessary).

Ultimately it may be best to just replace the engine, however I imagine sourcing one will be neigh on impossible. I wan't a totally standard engine ideally.

Finally, if it comes to removing the engine, is it possible to remove just the engine (Without the gearbox), if so how would I go about doing this, I do have an engine crane that will help im sure. I don’t really have room to have the gearbox kicking around if removed with the engine (car on driveway and very limited room in single garage).

Thanks so much in advance for you advice.

Olie

Looks like cylinder 2 has run weak/hot at some time and melted the side of the piston. Is the cylinder bore scored?

There are some vertical lines in the bore, I spent some time seeing if I could feel them with my nail which I couldn't, so they must be fairly superficial? Hopefully hone out?

I had a not dissimilar issue last year. Bought a ‘Sprint’ at auction, after a short test drive previously, drove it home and by then engine sounded rattly. Eventually took the head off and found bad corrosion of bore No1 due to water sitting in it for some time. Tried honing to no avail.

I removed and stripped the engine (yes it is possible to take the engine out and leave the gearbox). Took the separated block, pistons, crank, flywheel to an engine reconditioner I had used previously. He relined the corroded cylinder, honed all four, cleaned the pistons (especially ring grooves and repined), polished the crank and machined the flywheel. Pistons were reusable. That cost me just over equivalent of £550. I then reassembled using new rings, big ends and mains (all std size), plus new seals and gaskets.

Now, I am fortunate to have enough space under cover to do all the dismantling, store all the parts and reassemble.
If you have a new head on the way, then assuming you can get the bore honed, plus from the sound of it you need a good secondhand +020 thou piston you might be back in business. (Std bore size is 90.287-90.300mm, then oversize 0.020in = +0.508mm). If it can’t be honed, then investigate relining that cylinder. You’ll still need a piston though.

Before you start though, make sure you get hold of the correct workshop manual

Good luck
Geoff

I would say you are correct, the engine is knackered!

No good throwing money at it just to replace one piston (that is a +0.020" piston btw, the next size up to standard). If it were me I would re-sleeve it back to standard size & buy new pistons etc.. Someone may have a decent set of used pistons. Budget for around £1000+ for a full rebuild.

_________________
Sprintless for the first time in 35+ years. ... Still Sprintless.

Engines, Gearboxes, Overdrives etc. rebuilt. PM me.


1997 TVR Chimaera 450

Looks like its dropped the centre of a spark plug in there at some point in the past. I had a very narrow escape some years ago when the plug tubes filled with oil and disolved the glue on the Champion plugs. I had a missfire caused by the centre electrode moving into the cylinder, caught it before it fell in.

Thanks for all the input everyone, I appreciate it, helps calm the nerves as this is major for me having never gone this deep into an engine.

Update time.

Yesterday I removed the engine. What a beast! a fair bit heavier than an A series, and seperating the gearbox was fun, but careful jacking of the box so the engine could clear the subframe, and a lot of patience pulling the engine I liberated the boat anchor engine from the bay. I have placed a piece of wood under the front edge of the box to support it on the subframe while the car is without its engine.



A wooden dolly I made some years previous to move a tyre machine has come in handy.



A space was cleared to work on the engine, although not ideal, is better than nothing and atleast dry.



Having looked closely at cylinder 2 with good lighting, the bore does seem to be beyond saving and the piston has deffintley hit something and been mashed, I have also noticed a very slight ding in piston 1, but nothing that seemed to impact its ability to hold compression. Having said that there are also signs of water having been in the cylinder, and this is probably why the plug was siezed. Suspiciously the last reciept I have in the history file is for spark plugs and points being fitted on 14th November 1996, 5 days after the last MOT.





I have measured the bore with my new set of callipers (not something previously in my tool box) and got readings in the range of 90.31 - 90.33 across all bores ie Grade G - oversized according to the workshop manual.

I have started removing parts to try to lighten the engine for moving, the clutch was the first to come off which looks new! The flywheel came of next with the help of a 1960s 12 point Elora socket set, the rear main seal appears to be in a bad way a leaking a good amount.





The crankshaft pulley bolt came off easily with a mains powered clarke impact wrench.

Thats were I am at present. Oh and I have managed to source a full set of second hand Grade F original standard pistons. Sourcing the Pistons was the main hurdle, as £700+ for new is out of the question for me! Plan is as Mad Mart suggested, fit liners and return to standard bore, fitting my second hand pistons.

Any significance to GGGG stamped on my block? Just signifying all Grade G pistons?



I will keep you all updated with the engine rebuild.

Thanks,

Olie

The GGGG is the size of each bore from front to back, to match the pistons. As you intend to re-sleeve the bores it doesn't matter whether they are G or F grade but the m/c shop will need your pistons to match the bores. You can get a set of new pistons for about £550.

_________________
Sprintless for the first time in 35+ years. ... Still Sprintless.

Engines, Gearboxes, Overdrives etc. rebuilt. PM me.


1997 TVR Chimaera 450

Looks like detonation, that damaged piston. There's nothing wrong in re using sprint pistons. I did it many times but never fitted liners. I rebored 1850 engineblocks to std sprint size again. Maybe that's a cheaper option for you. When you can find someone that has an 1850 engine laying around for peanuts then it's just a rebore without fitting liners. Some 1850 have std factory fitted liners and you can't use these. At a complete engine it's easy to check when taking the sump off. You can see the liners fitted. If it's a lower end without head just sand the deck a bit and you can see if it's a plain block or a liner block.

Jeroen

_________________
Classic Kabelboom Company. For all your wiring needs. http://www.classickabelboomcompany.com

Thanks for the input and advice everyone.

The engine rebuild is underway, all updates will be in my project thread 'Sprint revival - XLK 467S'

Olie