Issues... urgent help appreciated, trackday on thursday!
Discussion
So I got the turbobeasty out on track on monday finally, however the turbo came loose on the exhaust manifold mid-session and by the time I noticed it the hot air had melted a few hoses etc - PCV breather and the wee ones to the boost controller. It also melted a dirty great hole in the cambelt cover, so it was pretty hot under there. Water temp was still fairly stable though in mid-90s, which seemed ok to me?
I've replaced/rerouted the hoses and my mechanic re-studded the manifold today (he had to drill out all 4 of them),but the boost seems to be misbehaving - instead of being responsive low down and pulling the 12psi it was set to before the incident, its lagging and then jumping up to 16... I didn't keep my foot down to see if it would go higher.
The hoses to the boost control are a bit longer now than before which could potentially cause some delay, but I'm guessing its one of two things -
a) I've plumbed the (manual) boost control in the wrong way round - would this have that effect?
b) The boost control has been stuffed by the heat?
I haven'tnow tried turning it up or down yet as I assumed it would be the same, but I might try that soon in case its just thatwhich fixed it.
The other issue is that the brakes went really soft/long in the pedal - I thought it was just old fluid but after bleeding they're still soft, I've just been checking the rear caliper adjustment so might bleed again after that, any other ideas? I can't see any damaged or bulging hoses, maybe the master cylinder is poked? It looks good and clean from the outside but you never know.
On the bright side it was hustling around really nicely for the 20 minutes of tracktime I got before discovering problems... but if I can't get it sorted tomorrow then I'll have to take the Legacy the 4hr drive for trackdays booked on thursday and monday instead!
I've replaced/rerouted the hoses and my mechanic re-studded the manifold today (he had to drill out all 4 of them),
I have
The other issue is that the brakes went really soft/long in the pedal - I thought it was just old fluid but after bleeding they're still soft, I've just been checking the rear caliper adjustment so might bleed again after that, any other ideas? I can't see any damaged or bulging hoses, maybe the master cylinder is poked? It looks good and clean from the outside but you never know.
On the bright side it was hustling around really nicely for the 20 minutes of tracktime I got before discovering problems... but if I can't get it sorted tomorrow then I'll have to take the Legacy the 4hr drive for trackdays booked on thursday and monday instead!
Edited by GravelBen on Tuesday 5th April 11:13
it could also be:
c) you still have a leak
I can't see it being your boost controller. If that was not working then you'd just be at wastegate boost levels.
Note that loosening turbo hardware on track is very common, the best fix, (barring replacing the lot with V-Band hardware), is inconel studs available from Trackspeed engineering.
There was/is a MASSIVE set of threads on miataturbo.net and miata.net on the issue, the inconel hardware was the final resolution. No amount of nordlock washers or safety wiring solved it.
c) you still have a leak
I can't see it being your boost controller. If that was not working then you'd just be at wastegate boost levels.
Note that loosening turbo hardware on track is very common, the best fix, (barring replacing the lot with V-Band hardware), is inconel studs available from Trackspeed engineering.
There was/is a MASSIVE set of threads on miataturbo.net and miata.net on the issue, the inconel hardware was the final resolution. No amount of nordlock washers or safety wiring solved it.
Could be a leak I haven't found, though mechanic must have missed it as well.
Actually just looking one of the breather pipes is a bit loose where it enters the intake pipe, could that be enough to cause oddness? It comes in before the turbo so I wouldn't have thought it would do much, but I've been wrong plenty of times before!
Thanks for the info re inconel studs, will keep that in mind if the problem resurfaces.
I can't remember, is your RHD or LHD over there?
Could be if its LHD that you've cooked the master cylinder, as it cant be very far from the Turbo on a LHD car?
Alternatively even on RHD I think theres two brake lines that run close-ish to where a turbo would be mounted, check there not fried also.
Could be if its LHD that you've cooked the master cylinder, as it cant be very far from the Turbo on a LHD car?
Alternatively even on RHD I think theres two brake lines that run close-ish to where a turbo would be mounted, check there not fried also.
GravelBen said:
Brakes are still crap though, you can just get it to lock a wheel (in the wet) but the pedal is on the floor.
Pads are more than likely goosed, or at least glazed, take them out and attack them with sandpaper then re-heat cycle them in to bed them back in.What pads are they incidentally?
Have bled twice (LR-RR-RF-LF), got a few bubbles out but no significant improvement.
Not sure what the pads are tbh, whatever the previous owner used!
But the pedal is very soft whether moving or not, so I'm pretty sure pads aren't the problem.
I'm wondering if its a booster leak or vacuum issue as I briefly got a bit more firmness from the pedal after checking/wiggling vacuum hoses, can't see anything wrong though.
Had enough for tonight, might drop it off to someone more knowledgeable in the morning.
Not sure what the pads are tbh, whatever the previous owner used!
But the pedal is very soft whether moving or not, so I'm pretty sure pads aren't the problem.
I'm wondering if its a booster leak or vacuum issue as I briefly got a bit more firmness from the pedal after checking/wiggling vacuum hoses, can't see anything wrong though.
Had enough for tonight, might drop it off to someone more knowledgeable in the morning.
Edited by GravelBen on Tuesday 5th April 12:33
MX-5 Lazza said:
Try bleeding through again. Start with the furthest wheel from the reservoir and work forwards.
OK so maybe you were right... pedal was much better this morning than last night (maybe trapped bubbles working themselves out as it cooled?) and I got mechanic to give it another quick bleed too (as I have to work!), its still not amazing but much better than it was. Also have some good pads (Bendix ultimates) on the way which I'll chuck in and see what happens.Edited by GravelBen on Wednesday 6th April 01:23
GravelBen said:
MX-5 Lazza said:
Try bleeding through again. Start with the furthest wheel from the reservoir and work forwards.
OK so maybe you were right... pedal was much better this morning than last night (maybe trapped bubbles working themselves out as it cooled?) and I got mechanic to give it another quick bleed too (as I have to work!), its still not amazing but much better than it was. Also have some good pads (Bendix ultimates) on the way which I'll chuck in and see what happens.Edited by GravelBen on Wednesday 6th April 01:23
If you've bled the pipes, and the calipers are all good and not leaking (you'd know), you are only left with the master cylinder.
Not sure if you're familiar with how they work, but it's a rubber seal that pushes the fluid out of the cylinder, down the pipes, and in to the calipers.
If the master cylinder has gotten very, very hot, it COULD (unlikely, but could) have melted the rubber seal in the master cylinder a little bit. It would mean the seal isn't perfect in the chamber, and it's only half-effective at pushing the fluid out of the cylinder.
They're normally very reliable, but then, they don't normally get very hot!
How close is the master cylinder to the bits that got very hot? Is yours a LHD model?
GravelBen said:
We're rhd in NZ so master cylinder is in opposite corner of the engine bay to the hot bit, though a couple of brake lines do run fairly close.
After a few hours drive tonight the pedal seems to have come right back to normal, so I'll keep an eye on things and see how it goes.
Sounds like glazed pads that are working themselves clean to me....After a few hours drive tonight the pedal seems to have come right back to normal, so I'll keep an eye on things and see how it goes.
The plot thickens...
Blew another turbo/exhaust manifold gasket out at yesterday's track day, seems the mechanic that re-studded it on Tuesday used studs that were a bit short and a cheap gasket. Had the spare time to fix it myself this time thankfully. It's also been pointed out to me that the exhaust lacking a flex-joint could be a significant contributory factor, so it's on the list to sort asap.
Anyway the thick part of the plot is that the soft brake pedal seems directly related to the manifold leak - it appeared again with that leak, and went away again when I fixed it. Inlet manifold I could understand, but not sure why an exhaust manifold leak would do it - maybe it confuses the turbo and affects vacuum that way. Good to have a bit more idea of the cause anyway.
Had a decent day of it yesterday as the gasket didn't let go until mid afternoon, found out at the end they had semi-official timing running and I was 9th fastest there so that was a nice consolation for car breakage. There was also an Iso Grifo out on track
lovely piece of machinery.
Blew another turbo/exhaust manifold gasket out at yesterday's track day, seems the mechanic that re-studded it on Tuesday used studs that were a bit short and a cheap gasket. Had the spare time to fix it myself this time thankfully. It's also been pointed out to me that the exhaust lacking a flex-joint could be a significant contributory factor, so it's on the list to sort asap.
Anyway the thick part of the plot is that the soft brake pedal seems directly related to the manifold leak - it appeared again with that leak, and went away again when I fixed it. Inlet manifold I could understand, but not sure why an exhaust manifold leak would do it - maybe it confuses the turbo and affects vacuum that way. Good to have a bit more idea of the cause anyway.
Had a decent day of it yesterday as the gasket didn't let go until mid afternoon, found out at the end they had semi-official timing running and I was 9th fastest there so that was a nice consolation for car breakage. There was also an Iso Grifo out on track
lovely piece of machinery.GravelBen said:
The plot thickens...
Blew another turbo/exhaust manifold gasket out at yesterday's track day, seems the mechanic that re-studded it on Tuesday used studs that were a bit short and a cheap gasket. Had the spare time to fix it myself this time thankfully. It's also been pointed out to me that the exhaust lacking a flex-joint could be a significant contributory factor, so it's on the list to sort asap.
Anyway the thick part of the plot is that the soft brake pedal seems directly related to the manifold leak - it appeared again with that leak, and went away again when I fixed it. Inlet manifold I could understand, but not sure why an exhaust manifold leak would do it - maybe it confuses the turbo and affects vacuum that way. Good to have a bit more idea of the cause anyway.
Had a decent day of it yesterday as the gasket didn't let go until mid afternoon, found out at the end they had semi-official timing running and I was 9th fastest there so that was a nice consolation for car breakage. There was also an Iso Grifo out on track lovely piece of machinery.
Time for the Incolen studs perhaps Blew another turbo/exhaust manifold gasket out at yesterday's track day, seems the mechanic that re-studded it on Tuesday used studs that were a bit short and a cheap gasket. Had the spare time to fix it myself this time thankfully. It's also been pointed out to me that the exhaust lacking a flex-joint could be a significant contributory factor, so it's on the list to sort asap.
Anyway the thick part of the plot is that the soft brake pedal seems directly related to the manifold leak - it appeared again with that leak, and went away again when I fixed it. Inlet manifold I could understand, but not sure why an exhaust manifold leak would do it - maybe it confuses the turbo and affects vacuum that way. Good to have a bit more idea of the cause anyway.
Had a decent day of it yesterday as the gasket didn't let go until mid afternoon, found out at the end they had semi-official timing running and I was 9th fastest there so that was a nice consolation for car breakage. There was also an Iso Grifo out on track
lovely piece of machinery.
FWIW none of the US guys use a gasket, just make sure both flanges are flat.RE the flex sections, yes it can help - moreso is a downpipe to gearbox bellhousing brace http://www.flyinmiata.com/index.php?deptid=4524&am... - but really it's the studs stretching that's causing them to loosen, Have you read the threads on miataturbo.net etc? they've been through everything you're going through I.e. flex sections, bracing the manfiold, nothing really worked until they put in proper studs.
My advice is 1 get or make the linked brace, then 2 get the inconel studs, then 3 actually use an entire trackday :P
RE the EGR. EGR is only active during cruise, as soon as you take your foot off the throttle the valve will close.
There should be a 1 way valve in the Vac port to the brake booster, it might be that it's failed. It certainly won't hurt to add an additional 1-way valve in there.
Not looked into those yet as i've been away again (snapping rally photos) and didn't like my chances of finding inconel studs at short notice, so I'll have to see how it goes tomorrow and follow your suggestions if it lets go again. The brace sounds like a good idea too.
Hazards of signing up for 3 track days within a week using a car that hadn't been on track before I guess!
Hazards of signing up for 3 track days within a week using a car that hadn't been on track before I guess!
Edited by GravelBen on Sunday 10th April 10:30
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