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Various hose problems


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I was doing some routine checks under the bonnet on Wednesday i.e oil fluids ect. and came across a hissing sound coming from what may be the servo? (I'm no mechanic by the way) It is a big round thing in front of the drivers side window and has the brake fluid connected to it. Anyway I took the engine cover/air filters off to access it and have discovered that the end of the hose has deteriorated and split, so I have temporarily taped this using electrical tape and a couple of cable ties to keep it tight. This seems to have worked fine and there is no air leak any more.

Since I had the cover off I checked all the other hoses and found one with big splits/holes in it, going into the bottom front of the inlet manifold and then into a little plastic valve. So I went off to VW and got a replacement hose (for an extortionate £15 and a 2 day wait for the part but there you go).

Friday morning VW call with part ready so drove to Chiswick, got it, got home, took the top cover off again, gave the area a good clean up and replaced the hose, all good. [Oh forgot to mention: there was a load of yellow oily gunk that seemed to have built up in the pipes going into the inlet manifold and into the air filter casing. I have cleaned this out as much as possible. My local garage advised me this is just years of build-up.] Whilst doing so I discovered another hose coming from the top of the engine to the air filter also has a hole in it! So I taped it up and used a couple of cable ties to prevent the tape from peeling and will get a replacement, eventually!

Bearing in mind the car has been running fine (at least in my opinion as this is my first car and I reckon I bought it like this! So wouldn't know any different) the car won't idle properly now! Before carrying out this work the car would sit comfortably around 8000-9000rpm and now it sways between 5000 and 8000, nearly stalling when at lower revs. My garage said that I need to let the car run for at least 30 mins. I have driven it for about an hour and a half and it has improved as it doesn't variate as much now...but it still does it, and the overall idle speed is now on average about 7000rpm.

I noticed a massive difference when changing gears as it feel a lot smoother and the car is almost more responsive but can't properly tell as pulling off in first gear is a little slower now due to the low revs.

Anyone have any advice here? Apparently the car is meant to tick over at around 9000-10,000rpm but this could be Chinese whispers...

Will take and upload pics if necessary.

Edited by skamuk1
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Tick over should be around 850, ideally you need to repair all splits so no um-metered air is entering the engine, and then erase the learnt values with vcds, it will eventually sel learn tho.

Could always try disconnecting your battery for 20 mins.

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Tick over should be around 850, ideally you need to repair all splits so no um-metered air is entering the engine, and then erase the learnt values with vcds, it will eventually sel learn tho.

Could always try disconnecting your battery for 20 mins.

Problem there is I don't have VCDS. Will try disconnecting battery now and get back to you. "eventually sel learn" - what do you mean by that?

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caretakerplus

I would recommend that you get the servo (correct name by the way) hose replaced with a new one PDQ. Not only will a catastrophic air leak on this hose mess up the engine's ability to idle, you would also loose all power assistance with the braking. - Brakes would still work, but by the time that you had figured out that you need to press the pedal a lot harder, you might have hit the car in front (or worse!!)

Regards.

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I would recommend that you get the servo (correct name by the way) hose replaced with a new one PDQ. Not only will a catastrophic air leak on this hose mess up the engine's ability to idle, you would also loose all power assistance with the braking. - Brakes would still work, but by the time that you had figured out that you need to press the pedal a lot harder, you might have hit the car in front (or worse!!)

Regards.

Ok, will go about changing the hose this week, as well as the other hose on the top of the engine. Your defo right about the servo hose, as I notice breaking is a lot stronger now than was before. Didn't remove battery in the end as the car seemed to be fine all day. tickover still not at 8500 though, its at around 8500-9000 when cold starting (i assume this is the choke) then when its warmed up it lowers to around 7500-8000, but the car is running fine.

Does anyone know how to adjust tickover?

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nige8021
Ok, will go about changing the hose this week, as well as the other hose on the top of the engine. Your defo right about the servo hose, as I notice breaking is a lot stronger now than was before. Didn't remove battery in the end as the car seemed to be fine all day. tickover still not at 8500 though, its at around 8500-9000 when cold starting (i assume this is the choke) then when its warmed up it lowers to around 7500-8000, but the car is running fine.

Does anyone know how to adjust tickover?

I'm hoping those idle figures are typo's :lol::lol: There is no easy way to adjust the idle speed as it's controlled by the ECU and is modified by info from the likes of the coolant temp sensor, inlet air temp sensor and some other inputs

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Just a thought call in to your local dealership or ring them and ask if there is any outstanding recalls, the servo pipe was recalled on some of the lupos can't remember if it effected the polo but it's worth a go.

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Ok, will go about changing the hose this week, as well as the other hose on the top of the engine. Your defo right about the servo hose, as I notice breaking is a lot stronger now than was before. Didn't remove battery in the end as the car seemed to be fine all day. tickover still not at 8500 though, its at around 8500-9000 when cold starting (i assume this is the choke) then when its warmed up it lowers to around 7500-8000, but the car is running fine.

Does anyone know how to adjust tickover?

I'm hoping those idle figures are typo's :lol::lol: There is no easy way to adjust the idle speed as it's controlled by the ECU and is modified by info from the likes of the coolant temp sensor, inlet air temp sensor and some other inputs

Oh, just realised lol, i meant 850-900 ect lol

My uncle (who used to be a mechanic) said I need to make sure all those air pipes are completely clear and that all hoses with holes are sealed or replaced. Is he correct, as this means removing a lot of hoses, some of which hard to get to. Also ensuring the air filter box is clean and the filters are ok.

The idle seems to be slowly improving, but still not perfect.

Edited by skamuk1
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Servo hose is very common in my experience. Has it come loose around the 90 bend going in to the servo?

I woildnt bother trying Vw as they will also sell you the one-way valve and obwould imagine it would set you back at least £30 plus vat, instead what I do is cut off the plastic pipe up until where the splits end. Then heat up the plastic hose well and then shove it over the inlet. Or alternatively,gut a section of silicone hose ( preferably thick walled) and two jubilee clips, then use that to connect it.

Also by the other pipe, do you mean the one going to the plastic valve attached to the throttle body by a metal bracket? If so, this is for the petrol tank breather. And will deffinatly effect the idle. What I did on mine was got a metre and a half of thick silicone tubing from gsf for £1.50 and and replaced it, but instead of making a stupidly tight bend like Vw did I took the hose closest to the expansion tank ans looped it round so there was little stress on it. Worked very well I think, and the thicker walls will not deteriorate like the originals.

Also, have you changed the temp sensor recently? If not inwould deffinatly recomend this, as it has a huge effect on the idle. When you change it I would also clean the thottle body properly, as this will fix most idle problems.

If all that fails, then perhaps the breather pod at the bck of the engine is hummed up. It comes off with three Allen bolts. I use petrol or diesel to svleanot out in a bucket. Butale sure it dry before putting it back. Also some silicone woildnt hurt around the seals.

Also, well worrth checking and cleaningtje engine earth on the gear box. Also worth gettingthe battery and alternator checked, asifthe powe isn't right then nothing will work right.

Hth

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Wow! I'll have a proper read/think tomorrow as its nearly 1am now and I have only just noticed your post. Lots of things to consider there. Hopefully my uncle will be with me tomorrow to help out and I will mention/suggest these things to him.

Thanks a lot, will keep posted!

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  • 2 weeks later...

Right... Since the weathers been bad I've not had a chance to sort the car out but tomorrow, if the snow holds back (only forecast fog here) I'm going to get the engine apart to have a proper look and attempt to fix this extremely annoying problem that causes me to keep stalling now due to lack of acceleration power!.

Correct me if I'm wrong... but I've got a thought in my mind that if the hoses were full of yellow gunk that the inlet manifold is also going to be! So was wondering how much of a job it would be removing it and giving it a good clean - what would i use to clean it, is there a procedure, rules, good idea bad idea, special tools ect.

I'm 90% convinced that the problem lies in the inlet manifold, and the hoses.

Does anyone have any advice for me before I recklessly rip it all out without any knowledge on the subject?!

Will upload pics of everything tomorrow as I will have the laptop with me in the car.

Thanks!

Also is it worth me getting vagcom to diagnose the problem?

Servo hose is very common in my experience. Has it come loose around the 90 bend going in to the servo?

I woildnt bother trying Vw as they will also sell you the one-way valve and obwould imagine it would set you back at least £30 plus vat, instead what I do is cut off the plastic pipe up until where the splits end. Then heat up the plastic hose well and then shove it over the inlet. Or alternatively,gut a section of silicone hose ( preferably thick walled) and two jubilee clips, then use that to connect it.

Also by the other pipe, do you mean the one going to the plastic valve attached to the throttle body by a metal bracket? If so, this is for the petrol tank breather. And will deffinatly effect the idle. What I did on mine was got a metre and a half of thick silicone tubing from gsf for £1.50 and and replaced it, but instead of making a stupidly tight bend like Vw did I took the hose closest to the expansion tank ans looped it round so there was little stress on it. Worked very well I think, and the thicker walls will not deteriorate like the originals.

Also, have you changed the temp sensor recently? If not inwould deffinatly recomend this, as it has a huge effect on the idle. When you change it I would also clean the thottle body properly, as this will fix most idle problems.

If all that fails, then perhaps the breather pod at the bck of the engine is hummed up. It comes off with three Allen bolts. I use petrol or diesel to svleanot out in a bucket. Butale sure it dry before putting it back. Also some silicone woildnt hurt around the seals.

Also, well worrth checking and cleaningtje engine earth on the gear box. Also worth gettingthe battery and alternator checked, asifthe powe isn't right then nothing will work right.

Hth

The servo hose has split at the end that it connects to the nipple in the servo unit yes, I have removed the hose, taped the end tight so that the split is sealed then I used a cable tie to tighten it on and prevent the tape peeling and shoved it back onto the nipple. Its a much tighter fit, but I don't think it will last forever. What sort of hose do you recommend and where would I buy it? Is it worth me replacing all air hoses with this stuff?

Yes, the other pipe is exactly that, it goes from the valve to the inlet manifold - This is the one I paid £15 for from VW, with about 3 bends on it and about 15cm long if that!

I don't quite understand what you mean by "instead of making a stupidly tight bend like Vw did I took the hose closest to the expansion tank ans looped it round so there was little stress on it.". Is there any way you can explain in more detail or show a pic mayb?

Have not changed temp sensor, wouldn't know where that is or where to buy one! Help appreciated!

I'll stop replying there for the moment as I think its best to take it one step at a time!

Thanks for your help!!!!!

Edited by skamuk1
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Hello mate. Thought I'd respond to your post in my old thread in here, so you've got it all on one page ;)

I've learnt a lot about cars since I made that old post, that hissing problem I described is just normal operation, and it usually becomes a lot more apparent when the air filter housing is off. Give it a try on yours, get a pal to quickly burst the throttle open and have a listen yourself (remove air filter housing), you'll hear the hissing coming from the throttle body hole (the main route for the air to get into the engine). This is fine.

A good way to check if you have any leaks on the inlet side is to hold your hand over the throttle body. It's a bit daunting, but if there are no leaks, the engine will stall. If there is a leak, the engine may continue struggling to run, running on air that is being pulled in past your hand, from the source of the leak.

But, the symptoms of an air leak on the inlet side are usually a high idle, not low idle/stalling. So I don't think your problem is caused by any leaks you may still have. Perhaps your car had a high idle before, due to the leaks you've described. According to VAG-COM, my 6N idles between 840-880 rpm.

This is where I become unsure, but my theory is this. As others have mentioned, your car throttle body (electronically controlled, takes readings from loads of other sensors) has become 'used' to the old leaks you had, and has adjusted your idle based on the extra air you originally had coming in with the leaks. Then, when you suddenly fixed the leaks, it's no longer used to the smaller amount of air entering when idling. As others have mentioned, it may take time to re-set itself, or maybe you can get someone on here with a full copy of VAG-COM to do a throttle-body adaptation. This really is where my knowledge ends, what I've described is just a theory based on what I've heard other people say about throttle bodies. I've never had an adaptation done on my own car so am not totally sure on the process, or whether it will solve your problem.

As for the pipe going to the back of the engine, that's the breather pipe, the one with the sludge in. It's usually common for them to have sludge in, and the pods at the back of the engine that the pipe from the air box connects to occasionally get rather blocked up. But I don't think a blocked pod will cause a low idle, I think you'd see other problems such as oil blowing past the rings and burning before-hand.. correct me if I'm wrong. But then again, there's nothing stopping you taking the pod off the back of your engine and cleaning it out, as someone else mentioned, 3 allen bolts hold it on. It's just a bugger to get to, might be best to tackle it from the bottom, unless the exhaust is in the way. In that case, you may need to move starter motor, inlet manifold and air box, which is quite the task for a beginner.

Oh and there's no harm in cleaning your air box as you queried, take that off (4 numbered screws), open it up (the other 4 smaller screws), put a new filter in, spray with 'carb cleaner' (Halfords sell it), wipe away gunk with rags and replace. When the airbox is still off, clean up the throttle body metal part (where the butterfly valve is) with the carb cleaner and a rag aswell, if this is all blocked it may actually be contributing to the poor idle.

In short, fix the leaks, but I don't think they are the actual problem. Give the whole air inlet system a good clean, replace filter, just as good practise. Failing this, get someone with a full copy of VAG-COM to look at it, or worst-case, pay a garage to do a throttle body adaptation (unless someone here disagrees).

Good luck

Edited by CWA
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The car does that every time I put my foot on the pedal and take it off again. So say I'm sitting in traffic, the car will be ticking over nicely, then as I go to pull off, it will start dropping in revs and sometimes cause me to stall, or pull off with no power whatsoever for about 5 seconds then it will all of a sudden pick up.

Also that sensor - the plastic is damaged so have bodged it up for now

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Youtube says those video links are private, I can't watch them, even when I log into youtube.

Looks like you have an EGR valve, what Polo do you have again? I'm afraid I don't know anything about EGR valves.. a fault with that might be having some influence.

In your third pic, the electrical connection that is cable tied.. I'm not sure what it's for either (don't have that connection on my car I don't think). Are you sure it has a connection like that?

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caretakerplus

For hoses which are subjected to vacuum, such as the one to the servo, it is essential that proper vacuum hose is used, anything else, particularly when hot can be flattened to the point of completely closing it by atmospheric pressure crushing it flat.

If you look at those pictures of Samco vacuum hose, you will see the that the wall thickness is probably greater than you would imagine it to be, this is designed to withstand atmospheric pressure i.e. it keeps the pressure OUT without the hose crushing,where other hoses are designed to keep it IN without it bursting.

Regards.

PS It doesn't have to be Samco, what it must be is VACUUM hose.

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Will fix video links when i get home, I'm just replying on my phone atm. I've had a bit of a result, after uploading all that stuff I diconnected my battery for 10 mins or so and then reconnected it. The car now idles fine and i no longer have the pulling off problem. The tickover still doesnt seem perfect but it think thats because I'm paying extra attention listening to it. But it idles much higher now, around 800. There also seems to be less smoke comming from the exhaust.

As you say above, the hoses do seem very weak when hot and are easy to squeeze (apart from the new one that i replaced which stays firm) so I may replace these hoses anyway, wont do any harm and not expensive. Also may look better if i use all red and black hoses. Color code a few things like the washer cap and so on.

Ill post the public youtube videos a bit later on.

Thanks for the help again!

Edited by skamuk1
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STILL DOING IT! WAS ALL FINE UNTIL YESTERDAY :x ITS NOWHERE NEAR AS BAD BUT IS STILL DOING IT EVERY NOW AND THEN....

GETTING BORED OF IT NOW!

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  • 1 month later...

Well i'm back, for the last time (i hope)!

Had my friend who is a Mercedes-benz independent mechanic have a look and he plugged in his diagnostic computer and found a loose oxygen (i think) sensor plug and once fixed he also re-aligned the throttle body.

The car was running horridly after he had done this but after a 30min drive it learnt the engines values and has become accustomed to the new mixture!

This has completely fixed it and if anything it seems to get better and better every time I drive it!

Problem solved!

Car is now for sale by the way! Check out the for sale section.

Thanks for your help everyone!

Edited by skamuk1
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  • 1 year later...
nige8021

^^ You could pay silly money to VW !! or look on ebay for 8mm silicon tube, I paid £5 for 1Meter and that was enough to replace all the vacuum pipes from the inlet manifold/throttle body

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