Big Ends?

[stutto 0]

I was happy this morning because yesterday I changed the discs, pads and all of the gearchange rods and bushes. I took it out for a spin and the gearchange felt better plus no more vibration under braking. Then it started making a noise, at first I thought that I had failed to tighten the heatshield over the 'L' pivot properly but now I believe it to be the big ends.

 

The noise sounds almost like a heatshield vibrating against something else in the engine bay but only occurs under load.

 

Do my assumptions sound OK or am I way off?

 

Assuming (always dangerous) that it is the big ends how hard is it to replace them (I have never done any engine work before) and what will the parts cost? What would I expect to pay if I got a garage to do the work? I appreciate, from reading other threads, that I should at least get the crank checked.

[ALEX 98 1 Cars]

shot Big ends make a knocking noise rater than a rattle.

Usually worn big ends give low oil pressure too.

Could be pinking or a blowing exhaust manifold.

[huzzer 0]

I had the same problem with my 1.9 after I rebuilt the head. I was worried I might not have torqued something up properly but after some investigating, turned out to be pinking heavily. Definately check the timing first.

[stutto 0]

It shouldn't be pinking as I only filled up with V-Power or whatever it is called on Friday.

[jim21070 2]

It shouldn't be pinking as I only filled up with V-Power or whatever it is called on Friday.

 

Fuel varies from tankerload to tankerload, especially the high octane stuff, so it could be detonating (pinking)

In an academic moment, have a read up on the differences between RON and MON Octane Numbering and fuel sensitivity. Basically, UK Octane numbers are based on the Research Octane Number which is a less stringent test than Motor Octane Numbers which more accurately relate to the conditions found in a real engine. 97 RON fuel may only MON test at 91 Octane or lower and the difference between the two is called fuel sensitivity. The Yanks use a PON system (Pump Octane Number) which is the average of MON and RON which is far more sensible. Fuel sensitivity is very dependant on the additive pack used to raise the RON to that advertised on the pump. Some work better than others and the refineries tend to use what it has plenty of. One day they my plonk loads of Benzine in to make it up to 97 RON and on another batch they may use something like Toloul. One works better than the other and gives a very much lower fuel sensitivity.

 

That said, as academically interesting as it is, I expect its not big ends or pinking, just something you have disturbed in all your work rattling around and making you fear the worst. Go over very carefully what you have done between the noise not being present and then being present and you'll find it.

[stutto 0]

Thanks for the replies, I will check over my spanner work before I start ordering shells - most likely tomorrow as I go straight from work to college tonight.

 

It really would not surprise me if I missed something as it was going dark when I finished on Sat. I forgot to mention that I changed the droplinks too.

[smckeown 1]

i've experienced a tinny vibration before, it was the exhaust heat shield vibrating

[deejay391 0]

When my big ends went i thought it was the heatshield. But it wasn't

 

Ive never done much work on the engine but with guidance from a friend we did all work together Not difficult if you have a engineering mind

[stutto 0]

I hope that it is loose fasteners on my ARB but I think that it is big ends. If it is not that is one evil echo.

[stutto 0]

I'm struggling to describe the sound but it is like 'clack-clack-clack' but only under load and it gets louder as revs increase.

 

I tried looking to see if oil pressure dropped off but it did not, does this mean that it could be top end?

 

I recorded the sound on my phone but by the time that the video gets onto photobucket the sound has been lost. If anyone could suggest an alternative I'll try to get the video available.

 

Confused.

[jim21070 2]

Diagnosing a noise like this is tricky without properly hearing it live and in the flesh as it were.

 

Problem is there are so many things that can make the sound you describe and not all of them are serious. One thought that has occurred to me. Is the exhaust manifold cracked or blowing at the joints, exhaust blowing, only firing on three cylinders, timing very badly retarded (you didn't knock the vac advance pipe off by any chance?) or something in the drive train. You were down in there before this all started. Only on load you say, that means when the car is moving under power so everything in the drive train is suspect, even the engine mountings.

 

Big ends going normally make a big, heavy knock and it's usually pretty unmistakable for anything else.

 

One sure way to rule big ends right out is to temporarily change the oil for some cheap 20W/50 and stick a can of Wynns in with it. This thick gloop will silence 'em on a temporary basis if they're on their way out. Worked for me on an old Volvo once. Knock, oil change and Wynnns until they started knocking again and time for an oil change.

 

I reckon it'll be best to get a forum member with an experienced ear to pop round and see you. I reckon there is someone local'ish to you who could do that.

 

If you were nearer, I'd be more than happy to do so..

[stutto 0]

Was going to whip the sump off tonight and have a quick look but I don't have a drain key and it just started raining.

 

I would be surprised if it is anything other than engine internals, but also glad. I'm sure that it is not firing on three and I did not notice this noise until I had been out in the car for fifteen or twenty minutes so I am reluctant to believe that it is something that I have knocked etc although with my mechanical prowess I won't rule it out.

[stutto 0]

 

Big ends it is then.

 

Is there a knack to removing big end caps? I have the nuts off cylinder 3 (working away from the flywheel) but the cap does not seem to move.

 

If I eventually get it off and the crank is not scored will it be OK to just fit new bearings? I really don't fancy engine out especially considering that it seems to be monsoon season.

Edited September 14, 2006 by stutto

[ALEX 98 1 Cars]

Oh dear.

Not just big ends, Mains will be shot too and The crank will be scored.

It's also possible that a conrod is oval too.

Before you go any further I'd start removing the engine from the car.

[richystran 7 3 Cars]

This happened to me too on my mi16! The tell tale copper deposites in the sump are what i had.

I though i would get away with just a change of bearings but it was not the case. My 3rd big end had no side to side movement when it had a new big end in it so it had ovaled plus you could see that the con had changed colour to a black and this is a clue that it was the one that over heated.

You probably wouldnt even see the scores on the crank they would be that small!

Its more that likly you wont get away with simply changing the bearings, its not a nice thing i know! What i done is buy another engine for £300 and im in the process of putting the new big ends i bought for the other engine into it and this engine is in good nick!

iF YOU NEED ANY HELP GIVE ME A SHOUT.

 

Cheers

Richy

[stutto 0]

Eeek!

 

 

The journal does not seem too bad, actually. What diameter should it be?

 

If my end caps are already numbered I take it that the engine has been apart before?

Edited September 17, 2006 by stutto

[ALEX 98 1 Cars]

Are all the bearings like that?

Id still be tempted to strip the engine fully as the crank WILL need grinding. You can't always see the scores, you need a set of mic's to see the damage.

Changing the big ends (the mains are also possible to change with the crank in place) will only buy you time before this happens again.

Trust me I've done it.

No matter how much flushing you do to remove the bits of metal you wont get it all out without stripping the engine fully.

Chances are the oil pump strainer plate is full of swarf too.

Edited September 18, 2006 by ALEX

[jim21070 2]

Agree wholeheartedly Alex, the whole engine has got to come apart and be fully cleaned.

 

A proportion of the debris will have reached the top end and it will do the cam, cam bearings and followers no good at all if left there. The oil filter will not have prevented it getting there.

 

Don't forget to strip and clean the oil pump and relief valve too or replace it.

[stutto 0]

Don't forget to strip and clean the oil pump and relief valve too or replace it.

 

Replace the relief valve, where would I source one of those?

 

Alex - only that cylinder is bad, it was the only one that had noticeable play when I removed the sump and tried to wiggle the end caps.

 

I have accepted the inevitability of engine out and will be visiting machine mart in the not too distant future.

Edited September 19, 2006 by stutto

[ALEX 98 1 Cars]

Looks like you've caught it just in time before the rest of the bearings were wiped out.

I'd take the crank to the machine shop though to get the rest checked out though.

I think you can only buy over sized bearings in a set so you might as well get all 4 big end crank jounals done.

£5 a journal IIRC.

[jim21070 2]

Replace the relief valve, where would I source one of those?

 

Sorry Stutto, I really must go back to school and learn to write properly..

 

I meant that if you have any doubt about the oil pump then replace the whole thing. This'll replace the relief valve too. Oil pumps are not that complex and are easy enough to strip, clean and check. As it is such a vital component and bearings usually fail because of oil starvation, a new oil pump is not a bad idea in any case.

 

If you do indeed find that only one big end has gone, then your problem is a blockage on the oil feed to it. Carefully check and clean thoroughly all oil galleries and passages in the engine so that this problem does not happen again due to a lump of crud circulating..

[stutto 0]

Thanks for the reply.

 

Another question:

 

I have three different sump bolts - two lengths of set screw and some cap heads. When it comes to re-assembly what goes where?

[ALEX 98 1 Cars]

Thanks for the reply.

 

Another question:

 

I have three different sump bolts - two lengths of set screw and some cap heads. When it comes to re-assembly what goes where?

 

The 2 (or 3) short screws go in the main bairing cap near the flywheel. The others are too long as thes holes dont go all the way through like the rest.

The Cap head screws are supposed to go at the front under the oil filter.

Haynes just shows a picture and says note where the cap head screws go.

Dont know why they go there though .

[stutto 0]

I have bought an engine crane. There will be more questions shortly, I have no doubt.