Broken vacuum connector

shanra · April 12, 2017

The vacuum connector on the plastic throttle body air box is broken exactly at the point where the arrow is. I inherited it this way and have glued and wrapped it in electrical tape in the past but it needs a permanent fix and any ideas would be welcome. I was working near it and remember wiggling it to see if my latest repair had taken (chemical metal and tape) and must have opened it or blocked it as my idle tickover has got very lumpy and the engine is running roughly. I had two weeks previously cleaned my throttle body so I can't see that as a problem I also cleaned my PCV valve which I have now replaced as so cheap. I have it off the car at the moment as I thought I had better check the distributor caps and rotors, the drivers side looks ok and yet to check passenger side I know one was supposedly replaced 4 years ago but for the life of me cannot see which one from the outside. I have also checked resistance of HT leads and all are around 15 and ignition coil leads about 3. Plugs were replaced about 20,000 miles ago (supposedly) and they are correct platinum ones. I have looked for the whole new assembly but with no luck as I suspect when selling an engine this probably comes with it.

runsgrateasanut · April 12, 2017

My small pipe also broke off. Slightly different in shape I think to yours and was ableto partly insert it.

Then best fix is using the sort of plastic cement glue they use on Airfix model kits. Goes hard as rock.

steve2006 · April 12, 2017

Seal off the broken bit with a small bolt and loctite them buy one of these, drill a new hole, self thread a suitable adaptor and loctite then reattach the vacuum pipe.

http://www.ebay.co.uk/itm/BSP-Taper-Thread-x-Hose-Tail-End-Connector-Brass-Fitting-for-Air-Water-Fuel-/121360796379?var=&hash=item1c41aacadb:m:mak604JmSq7b7P32JxHXWCQ

shanra · April 13, 2017

I have tried plastic glue but it's not strong enough. I think I may drill into existing hole as it may be the strongest joint and fit the connector unfortunately they don't make the taper end as small as I'd like 1/8" is actually nearly a 10mm thread if I'm reading it correctly. If I drill elsewhere it would have to be into the airbox itself and I don't think I'd get as much purchase on it there. Thanks for the advice and any more would be very welcome.

Farqui · April 13, 2017

This?

https://www.merlinmotorsport.co.uk/p/self-sealing-tee-with-10mm-push-on-sst10k

shanra · April 13, 2017

Thanks Lee that certainly is an option. I'd have to drill into the air box and use some sealant with it as the box is hard plastic but it is a possibility.

I'm guessing it's ok to drill it into the airbox as I think it's just recirculating fumes through the pipe anyway? I stand to be corrected as it's just what I think.

Farqui · April 13, 2017

John, I've used this type of pipe connector on flexi silcone pipes before without any issue.

So, I'd trim/blank off the broken connector and then fit one of these/similar in approx the same position.

Then hopefully the smaller flexi hose will still fit, fingers crossed...

Some of these connectors even include a big/flat self sealing washer that makes installation easier

Good luck getting it sorted.

shanra · April 13, 2017

I see the hose coming off this is one of two that connect to the Air Control Valve on the power steering which it seems a lot of people blank off so that would be another option.

runsgrateasanut · April 13, 2017

4 hours ago, shanra said:

I have tried plastic glue but it's not strong enough. I think I may drill into existing hole as it may be the strongest joint and fit the connector unfortunately they don't make the taper end as small as I'd like 1/8" is actually nearly a 10mm thread if I'm reading it correctly. If I drill elsewhere it would have to be into the airbox itself and I don't think I'd get as much purchase on it there. Thanks for the advice and any more would be very welcome.

1/8th of an inch is not 10mm more like 3mm unless I'm losing it!

Surprised plastic glue not storng enough as the part doesn't take any stress whatsoever. Very small bore pipe.

Mine has held well but if you applied it to tainted the palstic with something such as tape glue then you need isopropanol (?) to clean it first.

shanra · April 13, 2017

You're not losing it Stuart it's just how they measure it on these and don't ask me for an explanation because I don't know! If you click the link then look at the bottom of the eBay page it shows a conversion table. I have meticulously cleaned and prepared the surface but whilst it's not under much stress in day to day operations it's when you need to remove the air box and take off the hose that it always breaks, because then it's under the stress of my sausage fingers! I'll post a picture of the broken part (soon) and it will become clear why it's always going to break and needs reinforcement or another solution. Thanks for all the input.

I have had a breaker whom I asked for the part in January get back to me today asking if I still require it but if his pricing is anything like the quote he gave me for an aerial and motor I'll be fixing it myself!

runsgrateasanut · April 14, 2017

The Air Control Valve is vital for the engine to run properly.,Used to get problems with My W126's because of ACV's becoming sooted up. I've never heard of anyone blanking it off. Your difficulty is going to be because you don't have a flat surface to get a good seal the Tail fitting might prove very difficult, if not impossible, Better a screw in spud. Perhaps a spud for an LPG Inlet manifold may be the same size? You can check with Tinley Tech what bore size they are? Then self tapping in new position?

shanra · April 14, 2017

Well I've sent off for a

BSP Taper Thread x Hose Tail End Connector

@ £1.85 and see how that goes at the worst I'll have to buy the unit from breaker.

shanra · April 14, 2017

Here's the damage

shanra · April 15, 2017

Stuart it's the air control valve on the power steering pump not the idle air control valve. I should have been clearer.

GrahamG · April 15, 2017

John, I would use carbon fibre tow [untwisted yarn] to wrap around the join, wetted with long cure Araldite [not the 'rapid' cure because it will not wet the fibre]. Drill out and insert whatever metal tube will fit the hose or even use the broken plastic spigot but that might not give enough length.

Degrease with acetone, not alcohol for epoxy resin. Fix in place initially with epoxy and when set wrap as much tow as you can around the joint and larger diameter branch arm. You might end up with an ugly lump but it will not fail.

If you know a keen model aeroplane enthusiast he will show you how.

shanra · April 15, 2017

Thanks Graham I'd never even heard of carbon fibre tow before but ordered some and some standard Araldite.

runsgrateasanut · April 15, 2017

12 hours ago, shanra said:

Stuart it's the air control valve on the power steering pump not the idle air control valve. I should have been clearer.

My mistake on that. I just bored the hole to the size of the pipe, party inserted it and used air fix glue (can only be used after cleaning thoroughly) and have not had a problemt with it since. good luck with your fix john.

.

GrahamG · April 15, 2017

Just ensure you thoroughly wet ie. saturate each fibre of the tow with the epoxy. Do this with the tow/yarn on flat surface by gently pressing the resin in with a scraping action and a small piece of wood; not your fingures.

A plastic clothes peg will stop it unwinding.

Do the work in the warm and do not let the temperature drop below 21degC for 18 hours. I would leave an electric lamp 6 inches away overnight to provide warmth.

shanra · April 26, 2017

Well I drilled a larger hole and fitted a brass connector it split the plastic to the side of it so stuck that with Araldite Rapid (I ordered standard and ended up with this) anyway that seems reasonable with a clamp holding it together. I used Araldite around the connector and was going to use carbon fibre tow and Standard Araldite when I realised there is a stamp underneath on the plastic telling what it's made of, Polypropylene with 20% fibreglass, reading the Araldite instructions it says it doesn't glue this type of plastic. So the new plan is to now to strengthen it with fibreglass and hope for the best. I had given up when I split the side and had arranged to buy a used one but the breaker broke the plastic connector taking it off the vehicle. To add insult to injury my Mercedes has developed an erratic idle, it's obviously come out in sympathy for the Lexus! I also ordered some Beige rubber car mats from Carmats2u after a lot of time sending emails to and thro' and having sent them templates and paying for them they told me they don't do Beige rubber mats I don't know which bit of Beige rubber mats they didn't understand when I asked to have them made, but they apparently didn't. I've had better weeks!

Well I hope Brorocco wins in the 4.10 at Epsom and all will be roses again!

shanra · April 26, 2017

I'm going off the fibreglass idea I don't think it will bond it's a difficult material polypropylene I'm beginning to realise!

GrahamG · April 26, 2017

John, I did not expect the Araldite to actually bond the plastic; gluing polypropylene is like gluing butter.

My idea was that the tow being continuous length/s could be wrapped around the spigot and the larger diameter branch pipe it is attached so many times it would end up encasing both parts within a strong sheath/shell of carbon. .

They would be physically locked together rather than bonded by glue. Imagine in essence a very thick walled 15mm copper female T piece in domestic plumbing

Come on, stick at it!!

shanra · April 26, 2017

Mummify the mother, surround in a shroud. I hear you! Now to get some proper epoxy glue that doesn't set in five minutes.

GrahamG · April 26, 2017

John, is the complete duct too large to put in a box and send to me?

I have everything needed here [ Fleet, Farnborough ] in my workshop and would not charge you.

shanra · April 26, 2017

Thanks for your very kind offer Graham, it is fairly large and I do need to get the old girl back on the road as soon as possible with my Mercedes playing up. Thank you again.

shanra · April 27, 2017

On 26/04/2017 at 9:38 AM, GrahamG said:

John, I did not expect the Araldite to actually bond the plastic; gluing polypropylene is like gluing butter.

My idea was that the tow being continuous length/s could be wrapped around the spigot and the larger diameter branch pipe it is attached so many times it would end up encasing both parts within a strong sheath/shell of carbon. .

They would be physically locked together rather than bonded by glue. Imagine in essence a very thick walled 15mm copper female T piece in domestic plumbing

Come on, stick at it!!

Well that is such a strong bond I'd have to smash it with a hammer to break it and then it would be the polypropylene that would shatter! Now just got to put the car back together tomorrow. Brorocco won the 4.10 at Epsom at odds of 7/1 so things are smelling sweet again! Thanks for all the help it's much appreciated.

One thing I did do as the connector has a barbed end I sanded the edges down or otherwise it would take to fierce a hold that added to the fact it was 8mm and the hose to go on is smaller. I was unable to get the exact size when I ordered maybe I should have searched harder but I looked at a few companies and couldn't see what I wanted.