MX5 help

[immy21]

MX5 1.8 mk 2

Long story short it got drifted while overheating. I believe it was due to a seized thermostat. Compression test shown head gasket fooked.
So we changed head gasket, water pump, themostat, timing belt and a few other gaskets.
Head was skimmed, block was not, stayed in the car.

Everything is back together but won't fire, engine kinda seizes occasionally when trying to fire but doesn't when fuel fuse is pulled, spins fine by hand.
I'm about recheck belt timing but I'm puzzled as compression test is all over the place. I thought if belt was off all cylinders would be even.

Anyone know what compression these are meant to be?
Any thoughts and idea's?

Click to play this vid:

[Loopy_drifter]

I'd expect 12 bar + on all cylinders..

[jon200]

Which belt? Have you tried putting oil down the bores to see if the rings are damaged?


FS: HKS SSQV recirc inserts, S14 eccentric rear arm lockout washer kits

[immy21]

I'd expect 12 bar + on all cylinders..

Thanks

Which belt? Have you tried putting oil down the bores to see if the rings are damaged?


FS: HKS SSQV recirc inserts, S14 eccentric rear arm lockout washer kits

Timing belt, completely forgot about trying oil down the bores, I'l try that on a hot test next time working on it.

Exhaust was a tooth out, once corrected it fired up, idle and rev pritty good but odd thing is compression results still the same
I doubt it would start and run right if it was genuinely that poor compression. Had a minor water leak behind the pump so had to pull everything off and redo with some silicon to seal.

Just need to refil coolant, make it legal and test drive it now.

[skyshack]

Have you got the throttle held wide open for comp test?

[immy21]

Have you got the throttle held wide open for comp test?

No because I'm a stupid ****

I know how to do a pesky compression test, done it soo many times but the dumb ass forgot to hold WOT

[R3K1355]

Yep, IIRC that'll give you a lower number than normal.

So other than that does it run alrite?

[immy21]

Yep, IIRC that'll give you a lower number than normal.

So other than that does it run alrite?

Yeah seems so, just idle and rev'd it but seems good. Since the water pump didn't seal properly we were up late last night redoing everything since the timing belt had to come back off, so haven't had a chance to even get it hot yet.

It will probably be next weekend when I can finish it off and run it properly.

[immy21]

Done a hot WOT test, comp test results are the same. I figured either the valves arn't sealing and it just needs run or the head isn't sealing all that well.
Since it's had a heat cycle thought it's worth rechecking head torque with a different gauge. The first bolt came up 20ft short but I didn't feel comfortable in how much it's rotating to reach even minimum toque spec. 2nd bolt was the same but just as I'm about to give up tightening I snapped the ****in bolt. I guess it's due to old bolts or a warm block when tightening, ah well.
Compression with the missing bolt hasn't changed an still runs ok, trying to make a drift day next week so we will see if it holds up or not.

Mate drives this gold mk 2, I drive a black mk 1 but we share all the purchase and running cost for both cars between us, if we need to replace the engine or buy another and swap bits over so be it as they are both rust buckets anyway.

[Loopy_drifter]

Tried it with oil in the bores to see if it's rings or valves?

[immy21]

Tried it with oil in the bores to see if it's rings or valves?

Nope, forgot

[Loopy_drifter]

[immy21]

Done a hot WOT test with oil, still the same results, can hear compression is not as strong on middle 2 when testing. It's not using water or bubbling, oil doesn't look like it's mixing with water either.
Idle fine for about 30secs to min then runs lumpy and sounds like a rotary until throttle is touched That's probably just the ECU not happy about something, probably vacuum lines or lambda due to leaky exhaust.
Guess we will just run it now and see what happens, feel free to place bets

Trying to figure out how to keep the fan running with ignition on, can't find my answer via google.
On the mk 1 it's easy, I permanently bridged TFA and GND at diag port but the mk2 doesn't seem to have TFA, no secondary thermo switch on thermo housing no nothing to earth, and I can't find the relay to bridge that either. Any idea's how to do this on mk 2?

[Loopy_drifter]

At least you've narrowed it down to the valves...

[immy21]

Well, it survived the whole driftday start to finish last Sunday, missing head bolt didn't seem to make any difference. Oil and water didn't mix, no water loss.
I had a go in it for a few laps, was a pig to drive with lack of torque and really struggled to restart when hot to the point marshals were considering booting it off the track, mate had too quickly learn how to keep it running

We are probably going to do what we should have done in the first place, dump another engine in it or buy another, move bits across and scrap as it is a rust bucket.