MR2 Roadster - A Tale Of Woe, Maybe...

[Martin350]

Thanks for all of the constructive suggestions and advice, keep it coming!

steveo3002 said:

one my cars was running with a duff plug and that sounded like a terrible bearing knock....sorted the plug and good as new

I found that one the most encouraging, though!


Got frustratingly little done this evening; one final stud repair (drilling out and re-tapping one that snapped, it snapped again when I welded a nut to it and tried to wind it out) in the exhaust manifold, then power washed it out (still full of dust from the pre-cats removdal, and now a bit of swarf from the stud repairs), then blew it out with an air line.

I checked the air filter, it's not that bad but I'm a bit fussy, it'll get a new one.


I'm thinking that I'll check the other three big end bearings just in case, and if they're ok put the sump back on, oil in, cam cover on and then crank it over with no spark plugs in or exhaust manifold on and see if anything comes shooting out!

Edited by Martin350 on Wednesday 11th May 01:51

[Martin350]

Justin S said:

If it had come out the exhaust it would have been sat in the pre cat,which it wasnt, so its still in there somewhere. Easiest thing is a bore scope to see whats happening. Most work is the head off. Least work and potential internal damaging is new plugs and hit the starter. Interesting 'project' whichever way it goes. I guess these run cambelts rather than chains ? Maybe if the head comes off its worth swopping that as well. Good luck with it.

Thanks!

I have had a look with a borrowed borescope but it didn't have the flexibility for me to see the whole of the piston or the bores.

These engines have a timing chain, and that seemed nice and quiet when it was running properly, so I'll probably leave it, even if the head comes off.


I'll try and get a bit more done after work this evening.

[Martin350]

I did a bit of cranking by hand when setting up for the leak down test, and there were no surprises then.
But yes, I think it's still a good idea and I will do that first.

[Martin350]

Yeah, I had a look with the pistons at tdc and at bdc.
I'm struggling to get enough light down there to see the edges properly, and to get the probe angled where I want it, I should've made that clearer, but I couldn't make out any debris or damage from what I could see.


In the limited time I had this evening, I checked the other three big end shells, and as I suspected, nothing to report, but at least I know that now.

So I cleaned the old sealant off the sump and engine block, refitted the sump and put oil in.
Then I turned the engine over several times by hand, nice and smooth.
I then refitted the cam cover, unplugged the injectors and turned it over on the starter motor.
A good ten seconds or so and nothing came out, I think, and no horrible noises.

So, if I get time tomorrow I'm going to do a compression test, and if that goes ok connect everything up, put new spark plugs in, put the exhaust manifold back on and start it up! (I couldn't find an emoji for slightly worried face).

I suppose it's somewhere between and

Edited by Martin350 on Thursday 12th May 00:35

[Martin350]

Vitorio said:

So the horrible noises might have just been the dead spark plug?

So far everything suggest that with fresh plugs it has a decent chance of doing just fine, but that does give us the case of the mistery missing ceramic bit, considering the pre-cats in the exhaust manifold.

fingers crossed mate! hope it all goes well.

Thank you.

I'm rather hoping the horrible knocking was just because of the dead plug, as steveo3002 has experienced and mentioned a couple of days ago.

But yes, still a mystery about the missing bit!

I'm, sort of, looking forward to getting home tonight and trying it out.

[Martin350]

Yes, I think they are a terrific bargain at the moment.
I think in years to come nice ones will creep up in value.

The cubby holes behind the seats aren't too bad, easily enough for a couple of weekend bags, but as this is a second car it really doesn't matter.

[Martin350]

From what I've seen they aren't bad at all for rust.
I checked the MOT history for mine before I bid on it and there was no mention of it.
And my other half's 2004 model was very tidy underneath when she sold it last year.

Rear anti roll bars corrode, but it's not much to worry about.

From experience I can say that the MR2 is far cheaper to run than a 350Z.

There's the fuel for a start, especially considering a 350Z should be run on higher octane petrol.
Also prices of some parts like brakes and service items and any repairs are generally higher with the Nissan. And there's tax and insurance to consider.
A good MR2 should really be quite a cheap car to run.

As a weekend car I'd say the MR2, although very different and obviously not as powerful as the 350Z, is in some ways a lot more fun.
The MR2 is a sports car, the 350Z is a GT.

[Martin350]

Update time!

I got home this evening, did a compression test. The results were very surprising to me, I've never tested an engine and got more consistent results, all four were almost exactly the same!

Full of confidence, I put the cam cover and exhaust manifold back on, new spark plugs in and fired it up, and.....
































































... it still knocked like a good 'un!


I left it idling and did a quick as possible screwdriver-o-scope test on the cylinder head next to all four cylinders, and it seems there is still an issue with cylinder four, the one with the broken spark plug.

I had another hour or so to spare and made quite a good start on getting the cylinder head off, bugger!

[Martin350]

Something jammed in the head is my first thought, but sometimes with things like this it's something completely different and totally unexpected.

It's definitely not an engine mount, it's something inside cylinder four.

I'll get a bit more done this evening but I'm aiming to have the head off some time on Saturday, hopefully.

[Martin350]

Hi.

Progress has been slow due to limited time, and it's a complete arse of a job to do!



The head is ready to come off but, annoyingly, I need a longer one of these;



I asked this little fella, but he didn't have one either!

Edited by Martin350 on Sunday 15th May 14:51

[Martin350]

Thanks chaps, appreciate your help and support!

As it happens, my mate who I was with this afternoon had a longer spliney tool thingy!



So, off with its head!

And....


Well, not a lot at first glance;





On closer inspection, there was a small piece of hard metal, I suspect the mashed up spark plug electrode, on top of a slightly dented piston.
And that is another smaller bit of metal to the left of it.



And slight denting to the head, to the right of the two smaller exhaust valves.




So, was the knocking noise the small bit of shrapnel being bashed?
Or is it a little end, or piston, or piston ring..?

I'm tempted to get the sump off again and take the piston out for a look.

Edited by Martin350 on Sunday 15th May 22:05

[Martin350]

I did do that.

This evening I drained the brand new oil, took the sump and oil pick up pipe off and removed piston 4, the naughty one!

It doesn't look great, but it is a few hundred miles short of 100,000.
No broken rings, no detectable by hand play in the gudgeon pin, but it is a worn piston which has taken a bit of a hammering.



This is a better view of the piece of, probably, spark plug electrode. It's about 9mm long.



Do you like the hologram dinosaur ruler? They change position as you tilt the ruler, some of them are fighting!

It's about 2mm thick, measured with verniers, not the dinosaur ruler.

Slightly better view of the big end shell, looks good to me.



Now, these engines have been known to suffer with the bores ovaling, due to issues with the piston rings, oil holes in the pistons blocking and pre-cat failures.
It's all a bit chicken and egg, and I don't think anyone knows for sure what happens first.

Mine clearly didn't have a pre-cat issue, and with the rings off and the oil holes checked, nothing here either.
But the piston does show evidence of piston ring blow by.
Although, my mate who followed me home from collecting the car told me there was no smoke at all from the exhaust.



So, do I;

- Put it all back together now and hope the knocking noise was caused by the errand bit of metal

- Hone the bores and put new piston rings in, they won't bed in properly if the bores have ovaled

- Get hold of tools to tell me if the bores are ovaled (might be a good idea!)

- Get a new engine

- Open a bottle of red

With a car of such low value, it's tricky deciding how far I'm willing to go both financially and time wise, but I do want it running and working well...

Edited by Martin350 on Tuesday 17th May 01:26

[Martin350]

Thanks for the comments.

I think I will try and measure the clearance from piston to head to find out if the piece of metal found on top of the piston is thick enough for contact to be made.

If it is then I'll probably just put it back together and try it.


Thanks bearman, I'll keep that in mind if it doesn't go well!

[Martin350]

I was just going to post about that!

Evoluzione said:

Martin350 said:

I think I will try and measure the clearance from piston to head to find out if the piece of metal found on top of the piston is thick enough for contact to be made.

Not really understanding this bit, it's pretty obvious what's happened and irrelevant to going forward, why measure it? It'll probably be circa .7mm.

I just wanted to be sure that the knocking I was hearing was definitely the small piece of metal found on the piston.
But yes, I agree that it does appear to be quite obvious.
And you're right, the old head gasket thickness was almost exactly 0.7mm.

I've got a new head gasket set and bolts and I'm going to get it back together and see what happens.

Unfortunately I've been super busy all last week and this weekend so it will probably be into next week by the time I get to do any more with it, very frustrating!

[Martin350]

Thank you!

[Martin350]

Just thought I'd update and say where I am with this.

I've had very little free time recently, and drank quite a lot over the bank holiday, but I've got a bit done the last few evenings.

The piston is back in, the sump, cylinder head, camshafts, injectors & fuel rail, inlet manifold and the timing chain are back on.

Still got the throttle body, air inlet pipes, timing cover and tensioner, water pump, alternator, ignition coils, engine mounts, exhaust manifold, wiring and crank pulley to fit before I can turn the key.

I'm hoping to get the engine started this weekend and see what happens!

It'll either be or

[Martin350]

Haha, I hardly think this is the most exciting reader's cars thread, but thanks anyway!

Well, I got it bodged together with the absolute minimum to get it started up (I didn't want to get everything back on only to find it was a waste of time), so no water pump or water, no alternator or belt, and the exhaust not properly fitted etc. so I couldn't run it for long, but it started and....






















..... no knocking!!


But, not so quick with the


There was quite a bit of smoke from the exhaust.

As I've not run it for long, maybe about a minute in total of three runs, I'm not sure if it's the engine burning off oil I put in the bore and over the piston rings etc. before fitting them, as well as brake cleaner and stuff inside the exhaust manifold, or it's burning oil where I've disturbed one set of piston rings. I guess I'll have to wait and see about that.

Also, I've got a huge water leak from the timing cover, so I guess that will have to come back off to be re-sealed (there's no gasket, only sealant) but that isn't too much of a problem.

So, light at the end of the tunnel, I'm hoping to have it on the road and roof down next week, just as the hot weather hits the south east!

And I'm sorry, I've got an ancient mobile phone and couldn't video the first start up, otherwise I would have done.

I just want to get it out of the garage, give it the clean of it's life, and drive it!

[Martin350]

Yeah, that's what I'm hoping.

When I get time I'll get the rest of it back together (properly) and run it / drive it at least until it's up to temperature and see how it is then.

[Martin350]

Hi.
Well, with the odd hour or so here and there, I have taken the timing cover back off and found the cause of the water leak.

It was totally my fault!
The water pump has different length bolts and I got them muddled up, which meant that one of the longer ones bottomed out on the block behind the cover and instead of sealing the cover was pushing it away from the block. Silly me, a bit embarrassing really!
It also meant that when I put water in it quite a lot of it went into the sump, so the oil, and filter needed changing again!

Anyway, that is sorted, the timing cover and block have been re-cleaned and refitted along with the water pump and left over night for the sealant to cure.
This afternoon I put water in and no more leaks so far, although I still need to refit the cam cover, chain tensioner, crank pulley, breather pipes and a few electrical bits to start it up again, but I've had a few beers so leaving the spanners alone for this afternoon.

I'm hoping to have it all back together one evening this coming week. If not I've got the week after off work so will have plenty of tinkering time then, although the 350Z also needs some attention, but that's another story!

[Martin350]

I've been tinkering with my own cars for about 25 years, starting with much simpler cars like Minis, Escorts, Capris etc.
It's just a matter of practice and a bit of confidence, it does seem daunting at first, but as seen above I still make mistakes!

I am on 350Z-UK.com but very rarely go on there. It is a good site though, lots of info and some good sources for parts.
Your missus has impeccable taste!

And thanks!