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[moggy]

Hi all need some advice please.Changed the HBV the other day to see if it would increase the cabin heat.It made no difference at all,so i am assuming my H/matrix is blocked so i will try to sort that out.The problem i have now is after putting everything back together,i have an air leak from some where.At idle it wont stay stable and keeps hunting,above and below 500rpm.It was fine before i pissed about with it,and i have not removed any vac pipes to my knowledge.How is the best way to go about finding it,should i just spray carb cleaner all over the engine.And listen for a change in revs, or is there a better way of systematically going round the engine to see if i can find it. Wished i had not messed around now as it was running sweet as a nut.Any advice greatly appreciated.Dean

[05omegav6]

Did you refit the vac line to the new hbv?

[moggy]

Yes mate.

[moggy]

I have obviously disturbed some thing,but i am buggerd if i know what.

[05omegav6]

Is the rubber elbow still attached to the primary vac pipe non return valve?

[moggy]

Is the rubber elbow still attached to the primary vac pipe non return valve?

I don't know mate,i don't think it had one on it when i pulled it off.Dean

[05omegav6]

Is the rubber elbow still attached to the primary vac pipe non return valve?

I don't know mate,i don't think it had one on it when i pulled it off.Dean

It should have... be a good starting point if it's not visible halfway between the brake servo and plenum

[moggy]

Is the rubber elbow still attached to the primary vac pipe non return valve?

I don't know mate,i don't think it had one on it when i pulled it off.Dean

It should have... be a good starting point if it's not visible halfway between the brake servo and plenum

Hi mate i don't even know where the brake servo is.

[05omegav6]

How did you change the hbv?

[moggy]

How did you change the hbv?

Hi mate,removed windscreen wipers and scuttle,undid bagpipes,fuel line pipes and other things attached to the plenum.Then took the old HBV out and replaced it.I know i have fooked up some where,but don't know where.

[05omegav6]

Sounds like you've disturbed all the vac lines removing that lot... Needs someone to systematically work through it to find what's not right

[GastronomicKleptomaniac]

I must hold my hands up and say that it was me who did the HBV with OP watching over. It was running fine when it came to me, but the vac lines are all over the place, with some missing. So clearly theres something amiss, or something has coincidentally broken...

[05omegav6]

Ah, ok... Did you remove the main vac pipe from the side of the plenum to the brake servo? If yes,  was the hose reffited to the non return valve... Sits in space above the 135 coilpack plug...

They go brittle over time and it's stupidly easy to snap the spigot off the bottom leaving you with an open connection to the vac system. Other possibilities are:
1. Not refitting the vac pipe between the fuel pressure regulator and the throttle body (especially if the plenum has been liffted to one side)
2. Not tightening the main vac pipe fitting either at the plenum or the fitting connection.
3. Mis/displaced O ring (again not obvious if the plenum was moved to one side)
4. Not reconnecting the hose to the rear multiram.
5. Dislodging of the hose from the purge valve to breather bridge.

Basically work back through what was done and double-check everything. Likely be summat obvious

[GastronomicKleptomaniac]

Problem is the vac pipes are not right anyway, so tracing which ones have been removed and not replaced properly is difficult. Other problem is my ridiculous shift pattern, we ended up finishing in darkness...

It idles like a you-know-what, but as soon as its moving, OP reports that its just as normal. Does that narrow down where to be looking?

I'm utterly embarrassed to be honest, Ive done half a dozen, and I wrote the spigging guide, and this is the first one to not go right...

[05omegav6]

If it drives ok, then it's probably a small leak... But impossible to diagnose remotely