924Board.org

[Benji0301]

I have once again finsihed re-installing the engine back into the car (3rd time lucky? No Chance!! )

The car starts & idles at arounf 2500 revs, the starts hunting and eventually stalls.

There is a faint screeching sound that can be head every now & then. Generally whilst it is hunting for fuel.

The engine gets very hot very quickly but the thermostat doesn't open. I am now on my third thermostat. I think 1 & 2 were from a bad batch

I installed the distibuter as per instructiosn made sure line on crank shaft & oil pump line up. I also checked that the time belt sprocket & cam cover mark line up. I can see a -0 on th flywheel but it is not lined up with the mark described in the haynes manual. I checked that the flywheel was on correctly so knoq thats correct.

I did strip the air filter box & fuel metering had unit (not the metering head itself just the rest around it. to install a new gasket so may have inadvertently messed up the CO/Idele settings.

My question is what can I do starting from scratch to set the Idle speed & possible lean/air mix which is think why I am overheating so quickly?? Unless anyone has any other ideas???

[Mike924]

If it's hunting, there could be an air leak somewhere. This will also have the tendancy to make the mixture lean.

I'd start by checking all the rubber hose connections between the fuel distributor and the plenum. Less likely, but also possible, is the inlet manifold gasket. Also is the cork gasket around the fuel dist sealing properly. It can be fiddly to fit all the way around (and it's easy to crush it by over-tightening the bolts).

The mixture adjustment on the fuel dist doesn't affect the idle speed terribly. There is a separate adjustor on the throttle body for this. It seems you could do with screwing it in half a turn or so.
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1985 Porsche 924 'Lux', Kalahari Beige (my ex)
1993 Porsche 968 Coupe, Midnight Blue, 6 spd

'There is no substitute for a little grease under your fingernails.' - Chrenan, 924board.org

[seanski44]

sure the faint screeching isn't the alt belt slipping? this would obviously have a certain effect on your water pump and therefore engine temp... (p.s. grandma and eggs spring to mind, but the waterpump isn't seized?)
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1998 BMW Z3 2.8 arctic silver & red

1981 168HP 931 S2 blue/tan leather - SOLD
1985 121HP 924 2.0l na modded - SOLD!
1992 968 lux SOLD
1989 944 2.7 lux SOLD

[Benji0301]

Hi All,

Thanks for the responses, I fitted a new water pump & a new alternator. The new alternator pulley looked different to the one that I exchanged but I didn't think much about it at the time.

Now I look at it the belt sits deeper into that pulley than on the other 2. The oil pump & water pump pulleys seem flush with the belt but on the alternator pulley the belt sits quite deep down.

This may cause it to screech I don't know. I removed the belt last night & ran the engine to try & eliminate the source. The engine turned over much easier without the additional load & seemed to run faster. There was still occassionally a screech but not that often & not as loud.

I will nip the alternator round to a local friend with a lathe & see if he can make me new pulley out of aluminum/stainless with the right setting on the V.

I have got a company called CarTune coming round on Monday & they do the mobile tuning & diagnostic checking, only £30 for an hour so I might aswell get them to set up the timing & fuel/airmix correctly for me.

As an after thought is there anyway to bleed air from the cooling system other that via the red plug in the hose near the thermostat housing? I am worried that the overheating may be as a result of air trapped high up in the head.

[seanski44]

[torro]

The air should escape trough the red vent plug when the system is under pressure. It is the highest point and when the temperature is hight the air should release. It is probably best to vent the system when the termostat is open.

The termostat should open at aprox 80 degrees celsius, and the coolant should not get much warmer than that. On my restored enginge the temperature gets 80 degrees in less than 10 minutes and stays there.

I would recommend to flush the system once more, and probably add some radiator cleaner/flusher, could be rust blocking the coolant.
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-=Torro=-

[Benji0301]

I had to buy a new belt for this alternator which was 900mm long rather than 913mm on the previous alternator. So I suspect that this is the reason. However it does sit really low in the V so I might still get a bit shaved of the pulley to stop it sticking on release.

I suspect that I had a couple of bad thermostats as I filled the system and awaited the bubbles as directions of Mr Haynes but never got them. The engine got hot really quickly which may be the timing retarded or too lean a mix? Not really sure yet.

I tested the thermostats in a bowl of boiling hot water & they do open but only about a couple of MM & for only a matter of seconds which doesn't seem wide enough to allow a full flow? Or is this all that is required?

One last question in the rebuild I never replaced the little black elbow on the camshaft oil spray rail. Does anyone know where to get a new one in the UK?