Lewy's Z3 2.8 project - latest updates Jan '16

UK forum for general and technical discussion about the Z3 roadster

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Lewy
Joined: Mon 22 Oct, 2012 18:34
Posts: 203

  Z3 roadster 2.8
Location: Wolverhampton

Re: Lewy's Z3 2.8 project

Post by Lewy » Sun 03 Jan, 2016 23:12

Time for an update!

So this car has been left alone for quite some time, sold and then bought back! Before we get to this, my list was completed:

New axle carrier bushes - DONE
New diff mounting - DONE
Braided brake hoses - REARS DONE - FRONTS STILL TO DO
New handbrake cable - DONE
Paint Disc hubs - REARS DONE - FRONTS STILL TO DO
Brake shoe springs refit with cup washers - DONE
PAS cooling pipe replace - DONE
Replace corroded parts of exhaust
Caliper clean and paint - I have the rears off the car to do tomorrow - REARS DONE
New suspension all round - DONE (DIY)
Fit front lowering springs - DONE (DIY)
New Powerflex bushes all round (apart from recently replaced mountings)
Sort cam cover leak - DONE
Fit new thermostat - DONE
Spark plug change - DONE
New rocker cover gasket - DONE
Hunter realignment - DONE
New clutch - DONE (incl DMF)

So to move on, I've had a real problematic overheating issue which has really baffled me. After replacing the 'stat I just put it down to bleeding issues but as a precaution I replaced the water pump. After replacing the water pump I didn't then experience any overheating although earlier in 2015 I decided to sell the car. The lad who bought it then started to experience the same issues I'd had. It would overheat but by giving it the beans the cooling was more effective and the engine would cool down. I always regretted selling and after this chap was getting frustrated with this cooling issue I offered to buy the car back for the same money. All was accepted and I had the car trailered back to me. I basically got a free car wash out of it!

Finally I got the fan off and started to take the rad out and got at the 'stat. One issue. I mentioned earier in the thread that I'm very much learning on this car. When I fitted the stat previously, the arrow which needs to point up was completely overlooked. According to the internet, this is not a good thing! lol

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So potentially my overlooking the arrow position could have caused the problems? Do you agree? I also know these are real PITA engines to bleed so tried as best I could to follow the correct methods etc. I don't quite get why the arrow on the 'stat is significant, given there are no bleed holes and the unit appears to open evenly, not sure how it can operate differently depending on position if that makes sense? The motor has been compression tested and all is well (I hope).

Anyway, I really hope this is the breakthrough that was needed so that I can crack on. The Z has had a lot of replacement parts / upgrades and still has some way to go but I've kinda been stuck on the same problem for quite a while.

If it solves the problem I might treat myself to some new rubber for these:

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Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2115

  Z3 roadster 1.9

Re: Lewy's Z3 2.8 project - latest updates June '13

Post by Del » Mon 04 Jan, 2016 12:16

Once the thermostat is facing the correct way, normally the only reason it has to be swivelled in a certain position is to ensure that a little "air vent bleed hole" is positioned in the uppermost position. Is there a little hole or indentation in the lip at the point of the arrow?

Assuming the system is bled and circulating properly, the only reason I can think of that would result in overheating (relieved by driving fast with more airflow) would be a dodgy fan clutch.

Lewy
Joined: Mon 22 Oct, 2012 18:34
Posts: 203

  Z3 roadster 2.8
Location: Wolverhampton

Re: Lewy's Z3 2.8 project - latest updates June '13

Post by Lewy » Mon 04 Jan, 2016 19:36

Del wrote:Once the thermostat is facing the correct way, normally the only reason it has to be swivelled in a certain position is to ensure that a little "air vent bleed hole" is positioned in the uppermost position. Is there a little hole or indentation in the lip at the point of the arrow?

Assuming the system is bled and circulating properly, the only reason I can think of that would result in overheating (relieved by driving fast with more airflow) would be a dodgy fan clutch.
Thanks for your comments Del, my apologies I wasn't very clear. The engine will cool if the revs are increased, whether stationary or moving, so coolant seems to get forced through when the revs are higher but not otherwise. It kinda says airlock but having bled so many times and on the last occasion it did run for a while without trouble before it reared it's ugly head again. The arrow on the stat doesn't have any small holes around it at all so whilst I know that I fitted it wrong (i.e arrow pointing wrong way) I can't think if why this would affect anything. I hope it is as simple as this though as my problems will be solved, in this area at least! :D
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Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2115

  Z3 roadster 1.9

Re: Lewy's Z3 2.8 project - latest updates Jan '16

Post by Del » Tue 05 Jan, 2016 20:19

Haynes manual states:- “Ensure the thermostat is fitted with its bleed hole/arrow marking uppermost.”

Bentley manual states:- “ If the thermostat has a direction arrow or vent hole near the edge, install thermostat so that either the arrow or hole are at the top.”

All I can assume is that the stat (with an arrow and no hole) is designed so that it yields slightly in the region of the arrow to allow trapped air to bleed through the system :shrug

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