Overheating and Smoky engine.

Very curious!

I toppped up the coolant after letting it cool after bleeding and took car for a run, getting it properly warmed up. I didn't see any smoke whilst driving, but when back parked on drive on tickover, there was definate blue smoke coming from exhausts. So I'm now back to thinking it's the turbo smoking!

No, it was definatley the head gaskets!

After what, I think, must be about eight weeks (i lost count!) I finally collected my GTA from the garage today, after having the head gaskets done.

However, I'm not a happy bunny!

My car has the original exhaust still on it. When the garage removed it to work on the engine one of the mounting brackets broke off and left a hole in the silencer. They've tried to patch it up as best as they could, but it's obviously blowing from this hole in the silencer. Now, I've only driven it briefly, 5 minutes round the block, since collecting it this afternoon but it's not driving at all as i expected. I expected with the reconitioned heads and valves and also i had the turbo reconditioned, it would drive better than ever and be a real flying machine. But it feels SLOWER than before and i can't feel any real turbo 'kick' like i used to. I gave it full throttle in 3rd and it spluttered at around 5000rpm. Didn't feel very smooth at all. And it sounds rubbish with the blowing exhaust!

I probably can't really blame them for the exhaust, because it is the old original and was getting very crumbly and worse for wear looking and was due for replacement anyway.

I was wondering. Do i just need to keep driving it over the next few days to let everything settle and it will gradually improve and start to run better?

Will the blowing exhaust be critically effecting the performance, reducing the turbo boost, so I'm not feeling that turbo 'kick' I'm used to? Is this why it feels so slow and underwelming?

The exhaust wont make a difference to the performance. What you may have found is the people that reconditioned the turbo may have changed the actuator and its not set to the boost level it was previously, or even the garage that done the job hasnt correctly hooked up the actuator. Does the boost gauge go to the same place as before....

As everything has been off the engine id check the follow things.

Boost pipes : You do often forget to tighten the last jubille clip up, or one may be leaking

Check or small pipes and vacuum feeds. If the feed into the top of the regulator isnt connect it will cause a big drop in mid range performance. Wrong fueling can be the cause of spluttering...

Turbo Actuator : Either its not been adjusted in length by the recondioners for the correct boost, or the garage has not connected the actuator upto the wastegate, so the turbo runs very low boost after a lot of lag.

Dump Valve : Some garages get confused with vacuum feeds. There is a small pipe coming from the V6 pipe that goes to the turbo actuator, and a small pipe from the inlet manifold (after the throttle butterfly) that goes to the dump valve. If they have these the wrong way round, the turbo will still work like it should, but the dump valve will not hold any pressure, and leak alot of the boost, this could be the lack in performance.

Thanks David, I'll check these things out.

The mechanic did mention he'd adjusted the fueling because he thought it was running rich. Maybe he should have left it alone!

Really!?? Find out what he did. The only way you could make the car run less rich on the standard engine, is to pull the vacuum feed off the fuel regulator, or to turn the C/O level down on the potentiometer. Both of these would cause the problems you mentioned, especially the spluttering at high revs. Too much boost to too little fuel will blow the spark out.

I've been out again in it tonight for a proper, longer run. I took my brother along for a second opinion too. He's driven it before when it was healthy and he runs a fiat coupe 20valve turbo, so he knows how it should go and he agrees it's definatley not running right. It seems to feels like a boost problem, as in, there just doesn't seem to be any. My boost gauge doesn't flick back and too energetically like it used to and it only ever manages to reach about two thirds the way into the orange. I'm sure it used to flick into the wide black marking at the end of the gauge. Also, if the throttle is held at a steady 3500rpm in third and then floored suddenly - nothing! This used to be the range where it was on boost and would instantly accelerate, but it feels like there's just no boost there. And it struggles to accelerate up to 6000rpm, what little power seeming to tail off even more after 5000rpm, again like there's no boost.

About the fueling. The way the mechanic worder it was: 'it seemed to be running a bit rich (i don't know how he came to this conclusion) so i adjusted the mixture. I don't know how he did this.

Also, i noticed after my run, the engine cooling fans didn't come on. Do you know where all the connections etc are for these, for me to check.

Seems like i will have to take it back to the garage tomorrow morning with a few questions!

Cheers.

Does sound like boost then. The engine cooling fan on the left hand side for the turbo is next to the fan ( a two pin plug ) and there are two probes in front of the turbo which pick up the temp of the engine bay, these might not be connected.

DG wrote "The exhaust wont make a difference to the performance"

-not sure I agree on this. On my other car (a doggy rover 214) a hole in the silencer on my exhaust gave me real problems. I first heard a blowing noise (whilst on the M40) the car then had poor/no pick-up when accelerating, higher fuel consumption, max speed of 75 (downhill, wind behind you) - and a general feeling I'd lost 40% of power. Before anyone comments that all rovers are like this 70quid at kwik-fit did the job. It suprised me that a blowing silencer could impact performance like that. Can't say for sure if the same would apply to an Alpine as the exhaust design is markedly different - but correct exhaust function is an important determinant of performance. That said - you could still have other problems after the rebuild like DG said.

Turbo car's exhaust systems are completely different to normally aspirated exhaust systems. Non turbo cars work on a certain backpressure to promote scavenging of the cylinder chambers to draw in more intake air and make more torque and power. Any holes or leaks,or too little backpressure affect this scavenging effect and eat up bottom end torque and midrange acceleration

Turbo cars dont do this. The best exhaust system for a turbo car is no exhaust system after the turbo, as scavenging doesnt happen due to the intake being forced in, and then there is a huge restriction in the system, being the turbo itself. This is why supercharged cars at the same boost as turbo cars make more power, as there isnt any turbocharger restricting the exhaust. Any system after the turbo reduces power and torque, this is why larger turbos and straight through larger bore systems gain so much power naturally.

yes, after driving the car several times today, it definately feels like a boost problem, as in, there in none. Or maybe fuel. I'm still curious about the mechanics comment about adjusting the fueling. I've been back to the garage several times today and I haven't managed to catch the mechanic responsible for my car in yet, to query him. Maybe he's hiding from me! Anyway, would i be able to adjust the potentiometer myself? I know it adjusts by simply turning a screw, but how can i tell how much i'm adjusting it by? Would i need the diagnostic device plugged in? Would i risk messing things up completely or damaging something? Is this the CO potentiomter you mean David, a small black thing clipped to the right hand bulkhead?

Also, about the engine cooling fans. The manual says this:

1st instance:

With the ignition on, if the oil temperature is less than 60deg the fan motors do not operate.

2nd instance:

With the ignition on, if the oil temperature is above 60deg the fan motors start operating at 6 volts.
(This voltage 6 -> 12 volts is provided by a resistor located on the heating unit).

3rd instance:

With the ignition on, if the air temperature picked up by the sensor is above 90deg, the fan motors continue to rotate, but at 12 volts (resister on heating unit shunted)

4th instance:

With the ignition switched off, if the oil temperature is above 60deg, the fan motors continue to operate for two minutes at 12 volts.

Note:

Only the 60deg oil temperature switch controls the air extractor timer relay.
With the ignition switched on, the air extractor timer sends current to the 6 volt resistor and when the ignition is switched off it sends it to the 12 volt fan motors.


Can anyone tell me, do your engine fans always come on after parking up and turning the ignition off. Before my car went in for work, my fans always came on whenever I switched off the ignition, as long as the engine was up to tremperature. Surely, since coming back, the oil temp, even when fully warmed, is not running at less than 60deg. But my engine fans haven't come on once yet. I've checked the connections on the temp sensors by the turbo and the oil temp sensor on the sump, and all look ok and plugged in properly. And I'm not getting any warning lights either.

Finally managed to catch the mechanic and took him out for a run to demonstrate the lack of boost. He agreed it seems like a boost problem. He said before he adjusted the CO potentiometer it was reading 6% and it needs to be less then this to pass the MOT, so he turned it down to 2.5%. But he says this didn't seem to effect the running.

When they sent my turbo off for reconditioning, they said I could have it uprated to 18psi, but i told them to leave it at the standard 10psi.

However, he told me today, that the reconditioned turbo comes back to them with the actuator preset, they themselves don't adjust this, the turbo reconditioners do. And when the turbo reconditioners examined my old turbo, they claim it had already been uprated to run 15psi but they sent it back with the actuator set to standard 10psi as requested.

But as far as I've always been aware, my car is completely standard. I could be mistaken of course and perhaps it was uprated and i wasn't aware.

Could the turbo reconditioners be mistaken and they've mistakenly took a standard 10psi turbo to be 15psi and sent mine back adjusted lower, thinking they've set a 15psi turbo to 10psi, when in fact, they've set a standard 10psi turbo even lower? And so my car is now running with much too little boost.

The fact remains, whatever the actuator setting, there now doesn't seem to be enough boost. It wont even rev past 5500rpm!

Can a turbo reconditioner accurately set the actuator to a certain psi without it being on the car? The turbo technics web site says this about assembling reconditioned turbos:

The next operation involves fitting the wastegate and actuator assembly. These two components control the boost pressure the turbo will produce. All Turbo Technics Exchange turbochargers originally manufactured with an actuator, are supplied with an actuator. These are calibrated to the settings, specified by the original manufacturer, using the Orientation rig. This ensures that in most cases, no further boost pressure adjustments are necessary, after the turbo is fitted onto the vehicle. This saves time and adds reliability.

The last two sentences imply that further adjustment of the regulator might be needed once the turbo is back on the car. So do you think that they've simply preset my actuator all wrong?

The turbo people could be wrong, if your turbo was set up to run 15 psi, and your car isnt 'chipped' you would be hitting the boost cut all the time and the ecu would cut the ignition. Even if the car runs 10psi, it should still run fine up to the redline. Ive run mine at 5psi boost (below standard) and it still runs smoothly, just slower.

You cant play with the CO pot yourself. You would need an emissions tester up the exhaust to set this up. It is the black unit on the right hand side.

Have a look at the actuator rod on the turbo and give it a wiggle, to check it hasnt fallen off the wastegate rod. It should be very tight and not move at all.

The main thing to do is try and run some more boost. Take the front heat sheilding off from around the turbo, unhook the actuator rod, wind it in a few turns, and then rehook it back up...and then give it a spin. Repeat until faster!

Yes, I think they've got it wrong too. As far as i know it's a standard (non-chipped) ecu.

I checked the actuator rod and it's definately connected. It is boosting, but it feels like not enough. the boost gauge doesn't move as much as it used too.

I might try your suggestion of adjusting the actuator rod, if i have time before i take back to the garage.

On a seperate note, any more ideas why the engine fans aren't coming on? I've checked all the connections on the temp. sensors by the turbo and the oil temp. sensor on the sump and they seem ok. I unplugged them and cleaned the connections but the fans still aren't coming on. Any ideas?

Thanks for all your advice.

I never had any problems with fans at all, so I cant comment directly, but obviously check any fuses, or check there are no earths disturbed with all the work you had done on the engine.

It may be a coincidence that the sensors in front of the turbo may have packed up. Unplug the two wires and touch them together, this should make the fans come on...if not, then the fault is elsewhere..