Engine failure - swap compatibility?

[Skifey]

I'm at such a loss
It seems like the noises I'm hearing are nothing abnormal which leads me to the assumption that the starter is fine.

Putting that aside and coming back to the original rattle-bang-boom-oh-s**t-engine-dead moment; what actually IS there that can be the cause of this? Can a super fouled spark plug not sparking cause the engine to rattle, bang and shut off? Can a broken alternator do that? Can a stuck valve do it? Can a clutch or flywheel cause it?

I like to think I'm quite mechanically educated but in this instance I'm not afraid to admit that I simply don't know the answer.

[greenMachine]

First up, you may not find anything until you strip the engine - carefully. It may only become obvious when you see the damaged ring gear/starter pinion, or the clutch falls apart, or you see the broken pressure plate ... or it may not be obvious at all.

It may not be the engine, hence the suggested diagnostics in my earlier post to check out the clutch and gearbox. But the odds are that it is in there somewhere, but now that you have taken the head off, you cant actually run the car, let alone test drive it.

I think that doing anything more than the checks I have suggested (above) would be a waste of time. It seems like the rattle and banging cannot be re-created (unless those checks show it up). I think it is best if you concentrate now on dismantling the engine and checking it carefully as you go for any signs of failed components that might have produced those symptoms.

You might try and find an experienced hand from the local MX5 community to assist in this task, someone who knows what 'normal' and 'not normal' look like, as it is possible that you might miss the evidence.

[Nevyn72]

Engine overheats for a year and nothing I do fixes it.

* Cough *

Are we sure this is unrelated?

[RS2000]

That’s aside from the little tap/click noise it makes when the springs pop back and pop the camshaft back around yea? If so I did that already and it seems to be all smooth with no noise apart from that click every lobe rotation

I don't understand what you're getting at here. I've never noticed clicking when manually turning BP4W camshafts

[hks_kansei]

SInce you have the head off check the following:


Look at the piston tops.
Are there any dents? holes? cracks?

Look at the piston bores (with each piston at the bottom of it's stroke)
Any scratches? gouges? chips?


Now go to the head.
flip it over and look at the valves.
any cracks/chips/holes?
Do they all sit flush with their seats when closed? (you'll need to rotate the cam to get them to close)


Flip the head back over and remove the rocker cover.
Look at the cams
are the lobes all smooth teardrop/oval shapes?
any chips? gouges? or strange wear marks (such as a bright patch of metal on any)

have a look at the lifters underneath each cam lobe.
Each one should be two parts, a big base part which is the lifter, and a small metal disc seated in the top of them, the shim.
Are all the shims there?
do the faces (bits that rub on the cam lobe) look smooth?
do they have any raised lips on the edge?

[manga_blue]

Engine overheats for a year and nothing I do fixes it.

* Cough *

Are we sure this is unrelated?

Blown water pump was always a possibility. That's one of the reasons why I recommended he remove the ancillary belts to see if it made the noise with none of the ancillaries running. In fact water pump, alternator, PS pump and AC pump can all sound like a bucket of bolts if they have had a major internal failure.

[manga_blue]

Timing belt idler failure can sound pretty bad too.

[shirtz]

the mystery continues!

I thought starter motor but as many say that noise would be normal considering the heads off. some great advice above. unfortunalty it looks like more investigating is required.

[Skifey]

Are we sure this is unrelated?

Nope, got no idea haha!

I don't understand what you're getting at here. I've never noticed clicking when manually turning BP4W camshafts

So you're rotating the nut on the camgear and thus the camgear itself as well as the camshaft. The lobe pushes on the rocker arm and that extends the valve as is normal. Naturally though that rocker arm wants to spring back to it's original position and when the lobe pushing on it gets past the centre of the rocker arm contact point itself... it springs back up thereby pushing the lobe upwards and around. It happens really quickly and so it kind of explodes around and 'pops'. I dunno, hard to describe in short words.

SInce you have the head off check the following:

- Piston tops; no dents, holes or cracks. Only thing worth mentioning is that cylinder 4 is a slightly different colour but we all know the cause of that
- Piston bores; no scratches, gouges or chips in the piston bores that I could see
- Valves; Nothing wrong with the valves themselves but I can't be certain as to their position being perfectly seated while I'm rotating the camgear. It's hard to describe without writing another thousand words so I'll simply say that when I was rotating the camgear I was watching the valves come out one by one. The other valves whose turn it WASN'T to come out would slightly unseat themselves.
- Lobes; they all looked perfect and smooth to me
- Lifters; this is where I'm really not confident so I'll stop here and simply say I'm not sure. Same goes for the shims and faces.


Anywho! Thanks for all of the replies and info thus far. That's useful info from you GreenMachine and manga_blue as always. You're all legends!

I've decided to semi bite the bullet though since I've not got the time and experience needed to get this sorted. I've got a mobile mechanic coming around Friday to have a look at it. I'm hoping he'll diagnose the dam thing and I can give you all a conclusion. To be continued ladies and gents!

[Skifey]

Alrighty! Mechanics been over to have a look at it. I'll try to summarize below the key points

THE GOOD
- No damage to the cylinder walls as suspected. No scratches, no nothing
- The whole head looks good too. Valves are where they're meant to be, no abnormal noises or apparent damage.
- Alternator is good
- A/C Compressor is good
- Power Steering pump is good

THE BAD : Almost all a result of the overheating I had going...
- The head needs machining and service. It's got waterstone buildups as a result of overheating
- Head gasket will need to be replaced as will the exhaust and intake gaskets
- Ignition leads are completely fried. Black as hell. This means that I must be missing occasionally...
- Coil packs are the same and the plastic inserts are cracked.The bracket itself is broken as well. Go figure!
- My clutch is on it's last legs and it's worth replacing. Mechanic reckons it's got twice the engagement length it should so it's either a race clutch or dead
- Looks like the engine has been running lean as evidenced by the spark plugs
- Alot of my electrics and wiring is all hard and cracked. Again, overheating.

THE UNKNOWN & QUESTIONS
- Could have coolant running the wrong way in the block? The head gasket has two coolant jacket holes behind cylinder 4 that are blocked by the gasket although this could be standard?
- I need to replace the head bolts? I very minorly rounded one and something about them being built to yield. Can someone confirm this?
- Could the megasquirt be malfunctioning/not be tuned and thus be causing the engine to run lean and thus my overheating problem?

From here I'm going to need to weigh up the cost of all of the necessary parts (clutch is needed regardless so that's $500) and decide what's the most effective solution whether it be sourcing a secondhand engine or repairing the current and hoping for the best. I have no idea as to machining costs.

I'm also getting more and more curious as to my ECU. I know next to nothing about it and it could yet be the culprit of my overheating problem.

[Skifey]

Not too sure if anyone's still following along but for those who are I have another quick update and a brief question or two Any help and advice appreciated as always!

I've since taken the engine out of the car and removed the clutch. Flywheel still attached - that sucker is on soooo goddam tight >_< I'm taking the head to a machine shop to be pressure tested and rebuilt if all is clear. If not then I'll need to source a replacement and we'll finally be able to confirm the head as the culprit for this whole escapade.

In the meantime I'm sourcing parts; clutch, coil pack, spark plug leads, injector o-rings, engine mounts and starter motor (I broke my bracket when I removed the engine, woops). I do however lack the experience and knowledge in diagnosing some parts namely the clutch and engine mounts.
Is anyone able to tell and confirm from these pictures if either/or need replacing?

[StanTheMan]

The engine mount on the hot side.....if that's the one you broke, good chance it was broken without you realisng.

[StanTheMan]

If your 1.8 is standard output. Id get a standard tyoe upgrade clutch. in the vecinity of $250 not $500.
I fitted a Dailking clutch which is a slight upgrade to the OEM on a 1.6 flywheel. Its only done 5K m so far though. Perhaps a general consensus could help you out here.
Id also invest in a Wideand so you can tune your Mega-squirt. The spartan controller is cheaper than the one I have. I'm about to purchase my third Bosch 4,9 Wideband in 2 years of operating the MS2 with the bosh....Ive not had much luck. I'm currentky running without feed back. The map is pretty good.
on the other hand if you get a pro to tune your MS....expect about $1000. give or take a bit.

If your head is toast.....If you can actually find a BP-4W head.....I'd be thinking about a whole engine.
I spend about $400 on machining & sh*t on my head to get it refreshed. that does not include new Valve guide seals or any other seals if you decide to rebuild your existing motor

A full rebuild kit without bearings is at least $300. make sure is a Mazda genuine seal kit. I had horror stories with aftermarket valve guide seals on my B6. OEM are said to be the best ones. I used Mazda ones on my BP build & they are sweet.

[RS2000]

From the photos supplied, the clutch looks alright to me. Is the other side of the friction plate in similar condition? Do the mating surfaces on the pressure plate & the flywheel look ok?
The gaps at each end of the engine mount are manufactured, but are there any tears in the main rubber block? (usually near the bonded mountings top or bottom).

[Custardtart]

engine mounts are easy now the engine’s out , just buy a pair of oem ones. Clutch is a Exedy uprated one and looks fine, as RS2000 says, check the pressure plate and flywheel surfaces for scoring or obvious signs of wear.
I’m gonna be honest though and say that having read the whole thread and your overheating and knowing you’re not a particularly experienced spanner man, I’d sell the car cos I’d put money on it having had a LOT of tinkering with, you touched in electric/wiring issues!!! Then get someone from the club to help you buy a better one and get it serviced annually at a specialist.
If you’re really keen to have a fixer upper feel free to ignore me and good luck.