very annoying squeeling at low revs (tick over) 1.7 diesel

[chimp]

hi all

the problem is this when i start up initially i get no noise, but as soon as it gets a bit of gas the screeching starts, it increases as you go up through 1st sometimes second once past a certain amount of revs it stops however when you stop at a junction etc it begins again.

this goes on until its warmed up..... most of the time, usually at night i can do a reasonable trip and all will be fine but if stopped at some lights and i decide to put the heater on it starts up again as i flick the switch, same for lights, switch it/them off and it will usually stop.

there seems to be a definate link to current drain and it also seems worse in winter, damp conditions?

now before someone says alternator, ive swapped it, brand new one, and it just carried on the same, also new starter. the only thing in the link not replaced is the water pump which does have a wobble on it, probably due to the numpties at my garage slinging a single belt round it instead of the twin setup.

i cant see how something directly linked to current could be the result of the water pump, either way ive just put an offer on one on ebay

any ideas?

thanks in advance

chris

[ewenmaclean]

Hello,

I'm definitely no expert on this, or on the 1.7 engine, but is it possible the alternator belt needs tensioning or replacing? On mine there's a tensioner for that belt that you can adjust. When you use more current this will take a bit more load from the alternator, so it makes sense it'll be that belt. Depending on the belt arrangement for the water pump etc, maybe the extra load is having a knock-on effect elsewhere on belt drive system.... I can't be sure though as I'm not familiar with that engine.

Hope you get it sorted

Ewen

[chimp]

that does make a difference, but ive changed that twice and initially it did improve but deteriorated quickly. ive tensioned it several times since without much succsess?
im beginning to wonder if its the problem of having just the one belt slung round it, i had initially tried replacing the two myself but couldnt see how to get the one going from engine to water pump on, much lost skin ended in me going to the garage to have it done right. unfortunatelly they were lazy, did what i could have and charged me £40
i suppose its time for me to try again, thanks for the response Ewan

chris

[ringo]

I didnt have a twin belt setup on my 1.7d - just a single V belt.

Its obviously electrical load related - mine used to do it on startup when the alternator was on full whack charging the battery after it had cranked the engine over. It was the alternator belt slipping.

Are your pulleys contaminated? Is the battery in a good state?

Good luck,

Ringo

[jamesc76]

get a straight edge and check that the pulleys are spot on in line, if your changing belts that often either if out or your not tightening them up enough?

[Oldiebut goodie]

I seem to recollect someone else had this problem - it was the belt was the wrong length and was routed incorrectly. Any chance of a photo to check?

[chimp]

yeah ill get a photo tomorrow, i know for a fact that the 3 dont line up as the water pump has two channels so to speak one from the engine and the other to the alternator.
at the moment the single belt takes the path of least resistance, and like i said the water pulley has a slight wobble now.
ill pop to the van during my break and get a snap

i am running my leisure batt as my primary as my main died, it hasnt performed any worse saying that... saying that the other wasnt too good either
i may need to ask santa for a new batt for xmas

thanks for the help btw

chris

[BOXY]

I think a couple of the earlier posts are barking up the wrong tree?

there seems to be a definate link to current drain and it also seems worse in winter, damp conditions

Its obviously electrical load related - mine used to do it on startup when the alternator was on full whack charging the battery after it had cranked the engine over. It was the alternator belt slipping.

Switching things on certainly increases the electrical load on the alternator, but it doesn't increase the mechanical load. The alternator is spun by the engine and the current it produces is controlled electronically. Switching things on and off won't change the speed the alternator is spinning or make it work any harder (mechanically).

If the squeak increases in frequency with engine RPM then its got to be coming from something driven by the engine. I would start by checking any bearings on the belt pulleys, and then check the pulleys themselves are secure and lined-up. Moisture or contamination between a belt and a pulley will cause it to slip and squeal until the belt gets a grip (shouldn't happen with toothed belts). Dry bearings or side loaded bearing might squeal at certain RPMs and then go quite as they warm up.

If you can start the squeak by switching on something electrical then something spookey is happening? Is you van haunted?

[chimp]

Switching things on certainly increases the electrical load on the alternator, but it doesn't increase the mechanical load. The alternator is spun by the engine and the current it produces is controlled electronically. Switching things on and off won't change the speed the alternator is spinning or make it work any harder (mechanically).

this is what i thought, but yes i can literally turn it on at times?? haha haunted, i could deal with that! it is ex dutch airforce and i found exersize maps behind the dash so it is possible

there is a slight sideways pull due to the belt route which probably put the wobble on the water pump, iv just bought a new one so hopefully that twinned with two new belts will sort it.

i'll post that pic at lunch so you can see the route of the belt.

theres worse things that could happen but its really embarrasing at times, i get enough weird looks without screeching down the road aswell

i hope the pump comes before xmas

[ewenmaclean]

Hello Again,

I am not as knowledgable as some folk here, but the mechanical load on an alternator does increase with the current you ask from it - it has a big electromagnet which causes the engine to work harder.... I don't believe in ghosts!

Ewen

[Oldiebut goodie]

I think a couple of the earlier posts are barking up the wrong tree?

Switching things on certainly increases the electrical load on the alternator, but it doesn't increase the mechanical load. The alternator is spun by the engine and the current it produces is controlled electronically. Switching things on and off won't change the speed the alternator is spinning or make it work any harder (mechanically).

If you can start the squeak by switching on something electrical then something spookey is happening? Is you van haunted?

Bulldung!

The magnetic force of the alternator affects the mechanical load. The more juice that you want from it the more force is required to rotate it against the magnetic force. You can sap a whole horsepower from the engine overcoming the force in this way with some alternators.

[BOXY]

Oppps Looks like I'm not as clever as I thought. My specialist subjects are aircraft engines and industrial hydraulics so I'm off to Google alternators and electrical theory.

[BOXY]

Sorry to hijack the post but can someone tell me if this sounds right? Assuming an average voltage output of 13.5v and a current draw with everything running, lights, stereo etc of 70 amps. The power required would be V x A, that would be 945 Watts. If the alternator is 50% electrically efficient and 90% electrically efficient that would increase the required power to 2100 Watts. (945 /50% = 1890 Watts, 1890 / 90% = 2100). To convert this to horse power it would be 2100 / 746 which equals 2.8 HP.

If this is right, then just turning on my headlights and drawing 20 extra amps loses me 0.8 HP! No wonder the poor van squeals.