- My model of MX-5 is: eunos 03 1.6
- I’m based near: ulster
- I’m looking for technical help or recommendations on: engine issues
back story. may 21 eunos here from Devon 280k.kms Auto, drove for a couple of hundred k’s smoked for a week or 2 then stopped. only issue was on start up and high rev gear changes, a puff,a total rebuild of chassis susp and body, hood ,interior , wiring etc etc commenced… just back on the road early spring mainly for shake down and trial fits of a few things, still a wee bit of smoke, then a manual trans fitted, more miles, reckoned the guides well past it and were the main issue, good oilpressure and passed a serious ‘‘govnment station’’ Ulster MOT with hydro carbon measurements etc with colours held high, and blew the cam belt enroute home… searched and found an ex racer who had a spare old type B6 engine and wanted 30 quid, reckoned there was 100 kilometers on it, pulled the head, sent it for a total rebuild, back a couple of weeks later 260 lighter, left it with a good friend and wizard fettler who changed the head and called me last friday, to come over and see the results, and when he lit her up the exhaust had lots of grey white smoke pouring out, they had road tested it and it cleared, but both he and I said broken ring or stuck ring yet on the road it has plenty of power and always has had… i’m waiting on a compression test, however he now has the bottom end of the donor mill and so far all the bearings look new, are std size and he’s about to hone the bores and fit new rings…and rebuild again.more gaskets more seals more money. its fun isn’t it this disease we all have… i should have had more sense…w
Unless the head was skimmed in the first engine, I thought these were non interference engines meaning the snapping of the cam belt should not have caused any issue other than needing to replace it.
NickD, yes non interference and believe me i had alooksee at the belt before i replaced the cam box and gasket it had fresh signage numbers clearly seen on the top,it had been a rogue 10mm headed shoulder bolt ,not a mx5 part, somehow got in there that jammed in at the top side of the outer belt cover, no way for it to go anywhere it just chewed the side offa the belt, there was no issue just a cam belt kit and 500 miles later we can reuse all the new belt bits on the forthcoming engine rebuild…i hadn’t intended to link the cam belt issue to this deeper more serious issue…w
Attending the engine builder today, he showed me the 4pistons out of the donor short motor, having miked and cleaned and checked everything, yes it’ll rebuild nicely, i’ll hone it and fit those new rings, needed 4MM OIL RINGS… but more interestingly have discovered the cause of the oil smoke, i’ll bet money that the current engine in your car has the same issue maybe not all 4… every bloody piston has the oil ring seized, one i might understand but 4!!! It had been a race guys spare unit sat in a dry shed for many years thats probably why…pics later…w
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Delivering more parts today. my builder had a ring land cleaned and he on reflection overnight he had never in his life had any oil ring stuck, …others yes but never oil ones and showed me that where most pistons had tiny holes or slots behind the oil ring to let the oil scraped off the bores into the interior of the piston and into the sump …none in the mx5 ones, they had a small nick top exterior and same at the bottom to allow similar extraction, these are sited just above and below the gudgeon pin…if you look closely above they are apparent…w
THIS is a eunos, an auto no longer, they have 2mm oil rings, a manual has 3mm, and this short motor had 4mm, rings sourced in Germany,noone here had any ,so the rebuild of this different and lower mileage unit is underway, the engine and box have been removed completely, as its having a different and hopefully sweeter box refitted, Another issue has raised its head, my guy says the prop shaft is too short by approx 45/50mm, when i researched the auto to manual conversion i didn’t come across any mention even that the rear yoke on the shaft which bolts to the diff was a different size on an auto and required a mk1 spider fitted so the bolt holes would line up, so we did that i provided a mk2 shaft and the spider was refitted after that i had a shaft imbalance at 65mph and the new oil i had used to lube the box was slowly being spread as an anti rust treatment on the chassis underneath from box to rear valence because when it spun at 65mph it was chewing up the silver shaft at the box insertion point and doing same with the 25 quid seal.and nowhere in anything i’d read said that a propshaft would have to be be longer… please someone enlighten me… my wizard can machine me a spacer to enable correct dimensions to fit 'tween spider and diff with longer bolts…