Crunchy reverse

[syncropatrick]

Van has been leaking from both boxes.
Front diff from around drain hole. Nipped it up and topped up fluid - it took 0.5l which is quite a lot to top-up IMO.
Rear box leaking from around nosecone, cant work out why. Opened fill hole and oil came out, so not low there.

When reversing, hot or cold, I get a crunching, grinding noise from floor between cab seats, also a knocking noise from in back.
No issues with cornering, so don't think it CVJs, but prepared to be corrected. No unusual play in half-shafts. Not jacked up corners and wobbled wheels to see if its a wheel bearing.

For a while I've been suspecting the engine is at the wrong angle. It was swapped 18 months ago and since then the oil filler has been higher than previously and a struggle to get at through number plate hatch, and the rear UJ of the propshaft has been prone to snagging on the underbody protection bars, specifically the bolt on small cross-member, its easier to catch cud there and I seem to be cleaning out small rock more often. Its almost like the the engine is tipped forwards, raising the back and lowering the front of the gearbox. Propshaft doesnt run parallel with bottom of van. Should it?

Might I have an engine thats tipped forwards, dropping the propshaft rear onto the slide bars and causing a leak from the nosecone. In reverse this is aggravated and the prop is then also applying some undue stress on the front diff? I'm not sure how much the engine moves around, but can understand the theory that when reversing the engine is closer to the front than back. I guess dropping the slide-bars will help with diagnosing this.

Or is this the mad ramblings of a too-creative mind and I've got a fubar'ed front wheel bearing?

[syncropatrick]

Both boxes rebuilt 2 years ago BTW.

[HarryMann]

I would ignore thoughts about wheel bearing, they don't do much, and any sounds if they're bad are usually 'drones' or whines or hums, nothing I'm sure that realtes to your post...

Yes, look seriously at the engine angle but more importantly HOW it could possibly not be what it should. HOW could that have happened with a straight replacement?

.. unless some of the engine mounting rubbers are broken (common) or maybe the front gearbox mounts have slipped out of their lugs (was it all centred up nicely??) Engine bolts all tight. You didn't use a non-Syncro rear engine cradle did you

I would start by looking very closely (Mk.1 eyeball) at the underneath, take a cuppatea and lie there taking it all in, meditate a little, and maybe... Ay Uup, why that's laak that then?

[Aidan]

unless the rear engine bar has been swapped for a 2wd one by mistake then can't see how the engine height could have been altered

[syncropatrick]

The only spare part supplied was the engine, no mounting bars included in the spare parts bucket.

I'll take a look at gearbox mounting lugs and rubber engine mounts. Various engines have been in and out in the last 4 years, once by a reputable shop, so I'd anticipate 20 year old corroded rubber would have been replaced then. Where are the gearbox lugs?

Why is the gearbox leaking at the nose?

If its not engine rake then why am I getting crunching in reverse?

Will a worn front CVJ only be apparent in reverse?

Have I got a stone caught somewhere? Normally these pop out with a bit of forward/reverse so I'd be surprised if this was the case.

[Simon Baxter]

Do you have an irregularly high idle speed?
No synchromesh in reverse so if it has a high idle it will crunch.

[syncropatrick]

Idle is consistently high - 950-1050 depending on the day of the week.

Why would I hear the sound coming up between the cab seats?

[HarryMann]

If its not engine rake then why am I getting crunching in reverse?

.and why would engine rake have anything to do with crunching into reverse? Wouldn't have naturally made that connection myself, nor...

the noise coming up between the seats. Would it be a good idea to get another opinion, say Mark isn't too far, or up on a lift or over a pit is the best idea, chocks, brakes on and into Reverse and G and let clutch out, watch the engine/trans windup. Quite enlightening actually! Esp. the ringing of the prop, almost deafening at ear level

It's not that engine trans is moving backward/ forwards (translating) with drive take-up load, it is that it is 'nodding' nose down in FWD gears, & nose up towards the floor in 'REV'.. a very slight torsion but almost unnoticeable due to the way engine is supported.
So watch for the engine nodding and see what might be touching what, or where the compliance is being taken up.
Make sure you have a good driver when its over the pit who can heel and toe properly to keep all 4 brakes on as the trans winds up... if the clutch starts to smell, give a break before resuming, but a minute or two should be quite enough to spot whehther there are serious movement and/or alignment issues.


PS. BTW Did the van take any particularly BIG whallops underneath this year? Mine did, as Mark will testify (I think Linda went white for a minute, Jenny was too busy rubbing her head, but not serious harm done, thank goodness, shan't be doing that again for a while)

[Aidan]

Leak at nose, where from, is it the front seal or is it from higher up further back ? dew drop or damper ?

crunch sounds bad, and from area of noise the q is is it prop or is it front diff ? , remove prop to isolate - UJs will show noise directionally as will cvs

difficulty with engine oil filler possibly due to 2wd filler being used perhaps rather than the syncro one, if donor engine had it's one on perhaps

[hugomonkey]

just a thought, would it not be a good idea to check the magnet in the gearbox and see if you´ve got shrapnel in there just so you dont do any unnecessary damage
just to be sure

[syncropatrick]

Got a day off work, so will try some of these suggestions and maybe take some video with sound along the way.

No idea if 2WD oil filler pipe was used instead of 4WD one. I'll go part number searching. Where on the pipe is the number?

[HarryMann]

Yes that's a good suggestion, first thing prop off! Check UJs, take it from there. Good chance no crunch with prop off.

[v-lux]

Patrick, I was getting noise that sounded as though it was between the front seats running up to my 4th gear incident.

Presume now that it was noise from the gearbox (most likely bearing wear enabling gears to rub together) being transmitted via the linkage all the way to the front. Noise has disappeared entirely with a fresh box.

Checking your drain plug on the gearbox would be my first port of call, prop off next to isolate box from front diff.

[syncropatrick]

Right, did some more tests.
Cold idle is around 1100.
Once warm, idle is consistently 1050 +/- 25, so yes too high.
Once properly warm (30 mins of driving around) no more crunching at all. Yesterday when I 'warmed it up' I must have got just engine oil to temp, not boxes oil.
Van has pretty much sat since Salisbury in late Sep, so leaking could have been happening for a while. Its parked on packed hardcore so it's difficult to spot oil leaks. I've not seen them on ground so so far.
Slight ring when accelerating which might be propshaft.
From cold, it crunches in reverse, or freewheel reverse.
Listen from 10 seconds onwards.
http://www.flickr.com/photos/harmonywood/8261116162/
Leak from front diff was a dew drop of nice clean straw coloured oil. It was only coming from drain plug, now nipped up nothing coming out.

Leak from nose of gearbox is still a dew drop of black oil.



Gap between propshaft and cross slidebar is 2.4mm.


Off to buy some box oil in 5l jugs, as Comma 1l from Halfords is too expensive. Then back to drop prop and drain both boxes to examine magnetic plugs.

[hugomonkey]

take some pictures of the front gearbox mounts and where they are bolted onto the crossmember