Big end rattle

[Chris Edgar]

Beginning to wonder if the big end bearings are worn in the Tourer...(marina 1300 engine)
There is a light rattling when under fairly gentle acceleration.

It does not occur when the pedal is eased off or on over-run...which I am lead to believe that big ends do.
I don't have an oil pressure gauge fitted so no clues there. The warning light goes out smartly as soon as start -up though.

I wonder what the experts think of the symptoms?

If I drop the sump (new gasket reqd) & have a look & they appear worn I suppose it would then be a case of deciding to just replace the shells, with the correct size, or getting the crank re- ground
.......or is it always a crank re-grind?

[mike.perry]

More likely to be a noisy tappet. A big end would get worse the faster you revved it and the oil pressure light would come on when you slowed down.

[Chris Edgar]

Thanks for the reply, Mike.

I did check the tappets a couple of weeks ago although not having a starting dog to turn the engine over it was a difficult task compared to a standard fitted engine & I may have not got them all.

I am reassured by your answer though.

The Haynes MM manual suggests that b/e bearings should be replaced as a matter of course every 30k miles. I wonder if anyone does this?

regards,
Chris

[mike.perry]

30000 miles? The engine is just about run in. They will be telling you to drop the sump and clean it out every 6000 miles next If you use the rule of 9 and mark the valves as you check them there is no need to do more than 2 revolutions of the engine

[beero]

Sounds to me like it could be pinking. Retard the ignition a little and see if it goes.

[MarkyB]

I'd go with pinking too "a light rattling when under fairly gentle acceleration" is just about the definition of pinking, made worse with less gentle acceleration or going up hill.

[bmcecosse]

I agree - could be pinking. Try some top grade petrol. But DO get an oil pressure gauge asap!It is THE most important accessory. If caught soon enough - new shells are often a good cure. My engine was rattling merrily when I bought the car - had been run with low/no oil (there was none on the dip stick when I had a 'test run'!). I put oil in before driving it home....
I stripped the engine - shells were ruined but crank was fine - new shells all round (and a decent modern oil pump) and almost 10 years later it still runs with over 60 psi on the gauge and no rattles - despite being 'hammered' at every opportunity!

[Chris Edgar]

OK chaps,

many thanks for all the advice!

I am inclined to think and the more I think, the more inclined I am.... from what has been said, that it may indeed be pinking. I have to confess that I recently advanced the ignition a bit more that the book said...simply because it idled better!

The sound is like a very light diesel engine noise i.e. that very fast "detonation" sound.....so pinking could be the issue here, especially since, as soon as the foot eases off the pedal, it stops.

At any rate, it will be easy to check...hopefully tomorrow.

As for the premium petrol.. I had been told by Mark at the MM Millennium co. that these engines run better on premium...but it's 10p/litre more.... that's 9/- a gallon! Does it add up?
Be interested in anyones opinions on that score.

Yes, I do need to get an oil pressure gauge...it took me a lot of searching to see where the sensor fits into the block on this 1300 engine & at last I found it. Not obvious like on the Traveller 1098 block
.Looks like I will need to remove the dizzy to be able to do it.... however that holds no fear for me now, he said boldly

again, Thanks

regards
Chris

[bmcecosse]

It's in exactly the same place as the connection on the 1098 block! Unless the Comp ratio has been raised - you DO NOT need premium petrol. I suggested it as a simple/quick check to see if the pinking disappeared. Retard the ignition - and check the vacuum unit! That's why it's not idling nicely!!!! (I'm sure we have had this conversation before!)

[Chris Edgar]

We have had a similar conversation, regarding vacuum units, not present on my 23D. You suggested a 45D, which I will go for at some time.

The oil pressure gauge connection is in the same place but angled down & below the spin-off oil filter, which makes it not easy to get at without removing dizzy & oil filter cannister.

Anyway...ignition retarded this lunchtime & noise has now gone!

I have to say that I do feel rather foolish not having distinguished pinking from B/E bearing wear noise , but through the patience & expertise of yourself & others on this forum...the job's a good 'un & another lesson learned.

Thanks

Chris

[MarkyB]

Result! Much cheaper than a bottom end rebuild too!

[bmcecosse]

But if you get a decent dizzy WITH a vacuum advance unit - you will get the good idling and the good running - without pinking! And very probably better fuel economy too.

[Chris Edgar]

Yes, I will...got it bookmarked on e-bay.
Just waiting for the end of the month.

[bmcecosse]

" Just waiting for the end of the month. "" - aren't we all!

[MarkyB]

" Just waiting for the end of the month. "" - aren't we all!

Anything to do with a certain steam powered pickup?

[bmcecosse]

I wish........ still to check last week's Lotto ticket though!