Coolant issues, air issues or something else?

[Eye Guy]

Hi Guys,

I've decided to start a new thread for this, as it is potentially related but not the same queries I've posted about recently. Hope no one minds.

I've had a 1997 4wd Auto Diesel for about 18 months now. She has run sweet as a nut since I got her. However, we've been having quite the time of it recently...and this has come to something of a head today.

Firstly, I noticed a small loss of coolant. The alarm I have fitted went off once and the level never dropped below the bottom of the header tank. I eventually located the effected pipe, ordered a new one and had the garage fit it for me. They flushed, filled and bled the system.

Unfortunately, in my haste to be a good Bongo owner, I checked the coolant level and managed to leave the coolant tank cap off! This meant the temperature went up as I was driving but my temperature alarm showed this and I pulled over before she got too hot (max noted before stopping was 96C - usual running temp 89/90C - may have got a bit hotter when I stopped? ) I topped it back up and eventually got home (cap was still under the bonnet!) Took her to the garage and had them re-bleed and check coolant levels. Should have all been ok. Coolant remains topped up at a good level and no loss of fluid or change in level of header tank.

The garage noticed that an air pipe from the air filter was split (see my other recent post). I initially taped this and have now replaced it. The van was well noisy on the motorway and I thought it was to do with this pipe. However changing it has not sorted the problem.

If I drive over ~35mph and especially if I go >50mph, the van vibrates horribly and the dash rattles as does the steering wheel. It is noisy enough to make conversation difficult. There seems to be some loss in power but no clanging or banging from the engine. I can hear the engine underneath all the vibrations and it sounds ok?

Does anyone have any idea why this is happening?
Is this related to the coolant issues?
Is it worth me and my dad trying to bleed it again?
Is this a sign some damage was done?

Thanks for any info.

Cheers.

[Bongolia]

Edited.
When the vehicle was noisy with the split pipe did you have the vibration then?
Does it vibrate when stationary and revved?
Can you get a video of it and post it on here?
Else it could be unrelated to the engine and be tyres or wheel balance. If the wheel nuts are tight jack up a front wheel on each side and check for carbuncles or ovality (is there such a word?) of the tyres missing balance weights etc.

[Northern Bongolow]

4 w drive bongos can get knacked props, get your garage to check, the joints can fail, the diffs can also suffer bearing failures etc and can give vibrations, the center bearing on the front prop can also fail and vibrate
alloy wheels can give problems too particularly if they are not gen mazda ones with the correct centre hole size, tyres with bulges or the wrong sizes fitted to the wrong axle or different size tyres fitted to the same axle. also wrong wheel nuts, alloy wheels should have different nuts to steel wheels.

front crank shaft pulley is a 2 part rubber bonded affair, these can separate and vibrate, but they usually make a metallic chirping sound first.

[Eye Guy]

Engine seems fine when stationary.

Thanks for the comments NB on bearings, wheels etc. I will get the garage to check.

I presume this means you don't think it related to my recent coolant and air pipe issues? Sorry for vague symptoms.

Cheers

[Gasy]

Are you in eye in Cambridgeshire eye guy
If so I'm only up the road

[Bongolia]

Engine seems fine when stationary.

Thanks for the comments NB on bearings, wheels etc. I will get the garage to check.

I presume this means you don't think it related to my recent coolant and air pipe issues? Sorry for vague symptoms.

Cheers

Its likely related to tyres/wheels or prop I would guess.
Let us know the outcome as it forms useful info for others.
Good Luck and I hope whatever it is is cheap to fix.

[Eye Guy]

Thanks Gasy but I'm in Glasgow. Bit of a walk

I've booked in the garage for Monday. Cross your fingers.

Cheers.

[cmm303]

Can you confirm if vibration relates to road speed or engine speed. You mention it is bad >50 mph which would roughly equate to >2000 rpm. See if you get similar vibrations at similar revs under load in 2nd or 3rd gear (e.g. up a hill)?

This will help isolate the problem to the engine or the transmission/running gear.

Do you get the vibration when coasting at speed or does it go away as soon as you lift off the accelerator?

[Bongolia]

Can you confirm if vibration relates to road speed or engine speed. You mention it is bad >50 mph which would roughly equate to >2000 rpm. See if you get similar vibrations at similar revs under load in 2nd or 3rd gear (e.g. up a hill)?

This will help isolate the problem to the engine or the transmission/running gear.

Do you get the vibration when coasting at speed or does it go away as soon as you lift off the accelerator?

Good question.

[Eye Guy]

It is booked into the garage Monday. I have been laying off driving it for obvious reasons but will have a try over the weekend and see if different with power v freewheeling.

Interestingly, I have just re-read the comments above and my Bongo has always had a chirp/ squeak on every rotation of the wheels. I thought it was at the front at first but think it the rear. Only notice it in the summer when the windows are down! I asked the garage about it and he said I have a 'leaky diff' at the back, which wasn't doing me any harm. Wonder now if it is related....?

[Eye Guy]

Ok. Quick update after a little spin tonight. Vibrations/ shudder still present even when freewheeling. Worse the faster I go.

The chirp, chirp, chirp she's had since I got her has always stopped with light pressure on the brake pedal. I assumed it was a disc running or something. Both garages I've had it to over the 18 month ownership haven't seemed inclined to do anything about it. Like I said, wonder if it's related.

[cmm303]

Ok. Quick update after a little spin tonight. Vibrations/ shudder still present even when freewheeling. Worse the faster I go.

The chirp, chirp, chirp she's had since I got her has always stopped with light pressure on the brake pedal. I assumed it was a disc running or something. Both garages I've had it to over the 18 month ownership haven't seemed inclined to do anything about it. Like I said, wonder if it's related.

It doesn't appear to be engine related.
I'd check for sticking brake callipers, warped/worn discs​ and play in the wheel bearings (these usually hum) causing the chirp noise.
As NB said, check drive shafts, joints, bearings and wheels starting with suspected axle.
You could have more than one problem.

You haven't lost the balance weights off a rear wheel by chance?

[Gasy]

Think you said the rear diff is leaking
Northern bongo has Sussed this problem out and it's usually a blocked diff breather causing pressure build up and leak of diff seal
Think there's breathers on both diff and something else
He will be along to confirm soon where the others are and how to clear
I carnt remember

[Eye Guy]

Thanks Gasy. I wonder if it is this rear diff problem (an area of the Bongo that I understand not at all). Hopefully Northern Bongalow will be along before I go to the garage tomorrow with some advice. Cheers.

[Northern Bongolow]

it could be anything mate, its really hard to help more from here, all we can do is knowing the bongo as we do is to steer you to the possible culprits that have come up on here before, or we have had ourselves in the past. it could be owt from a bulge in a tyre squeaking on an ally wheel, to loose or wrong wheel nuts, wrong wheels, to bearings, brakes, props.
what makes this work though is when you come back next week when youve been to the garage and tell us what he found aided by 46 sheets of printoffs of this thread
good luck ,