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Engine knocking..


Howard81

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Spitfire MKIV with a 1500 engine..

I noticed a few days ago that when you start the car from cold the engine makes a rattling knocking sound for about a second, then runs as normal. It's quite a 'heavy' sound and its never done that before. If the car is warm and you restart, it starts as normal with no knocking.  Driving the car around London has always been okay, but that's all been under 40mph.

Yesterday, I took the car on the M4/M25. The knocking has returned.. It only does it above 40-50mph Only just about audible. It only appears when you are cruising as a steady pace, then push the accelerator a fraction to slightly maintain your speed. It's constant under very slight acceleration, if you accelerate harder it goes away.

As far as I can see nothing is loose in the engine bay. Oil was changed just before Christmas and has good levels.

I do get a flickering oil pressure light when the engine revs drop below about 600rpm, but no other time.

Any advice? Or am I just being a bit on edge given my track record with these engines? :lol:

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Have you a pressure gauge?
The light is only a fail safe  and will come on when you have only a few pound pressure...like when you are out of oil
If ticking over it will be around 25 when warm and  at 3k 65pound approx
However if you are getting an engine knock all the time then it sounds like crank wear
How old is engine? reworked? etc
More detail please  

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That sounds like you need new bearings.

Can you fit a gauge to get a confirmed pressure.

1500's are prone to it, and will carry on for many many 1000's of miles with the death rattle at start up and a knock under load.

But... the ends are still wearing and the pressure slowly dropping, and then suddenly no.3 rod makes a break for freedom out of the side of the block.

Though I suspect the noise by then will be too loud for you to ignore.

Cheers

Colin

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I suspect the best thing to do is drop the sump and fit some new bearings. Or at least check them. But if in there might as well replace. Amazing what a difference a new set will make, even if there is wear on the crank, and even the odd scratch mark. Best £40 you can spend in this situation (I reckon anyway)

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There isn't an oil pressure gauge fitted..

Engine only knocks on slight acceleration above 40 mph, and it's not loud.  The clonking rear driveshafts are much louder ;D (I've got the bits to fix those).

Exhaust is clear of anything that it could knock on.

I've now adjusted the carburettors to idle at about 800rpm, so the oil light no longer flickers.  When starting the car, it immediately goes off as expected.

Engine is a complete unknown.  Car is a 1970 MKIV, engine number is FP39E, indicating that it is a 1500 unit that started life in a Midget.  No idea when it was fitted as the logbook still shows the original number, and I've no idea how many miles the car has done as it came with a broken 1500 speedo fitted..

How easy is it to drop the sump?  Can you do it without removing the engine?  I don't have a garage, and the only space to work is at the side of the road in London.. not exactly ideal!

I do have a totally dismantled Toledo engine that has a good crank, new +10 bearings and a rebuilt cylinder head.. it's missing a few bits - cam, head studs/nuts, pushrods, core plugs.. but ideally needs a hone, new rings, etc.  But it's doing a swap that is a problem!

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A thought.. you say the knocking at cold start up has happened after you did an oil change?  Is it possible you have used a new filter without the anti-drain valve? This would allow all oil to drain from the filter at rest, giving no oil pressure until the pump has filled it when starting from cold.

However, I agree with the others above, it does sound as though the big ends are on their way out. Quick and easy to change with the engine in situ. Drain oil; take off sump (may need to raise engine slightly to clear the oil-pump); undo all big-end caps; push pistons up the bores about an inch; swap old shells for new ones (you need to take old shells out before you can order new ones, in case old ones are 10, or 20 etc thou undersize); keep everything as clean as you can; replace big-end caps with plenty of oil on the shells; torque up the bolts (should use new bolts - but it's up to you); new sump gasket; refill with oil and crank over for a while with the plugs out to get a bit of oil pressure up before starting it.

Very quick, except having to check the old shells for size before you order the new ones, unless you know the size already of course.

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"It only does it above 40-50mph Only just about audible. It only appears when you are cruising as a steady pace, then push the accelerator a fraction to slightly maintain your speed. It's constant under very slight acceleration, if you accelerate harder it goes away."

That is an excellent description of big end rattle.  Present on float but goes away on drive or overrun.

Fits nicely with rattle at start-up.

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Okay, looks like I've got a bearing change to do :'(

Has anyone done this before who can advise me on any tips and tricks?

Doesn't the front crossmember get in the way to make things awkward?

The oil filter I used has the correct anti-drain valve, and I'm pretty sure the one I took off did too.  However, I have no idea on the engine's history.

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what oil you put in, !!! no some thin stuff,
I put some 10 60 oil in mine last change, and lost over 10 psi at 2000 rpms,

or you can buy some 25 60 oil or better still some 30 70 oil,  or some 40 70 oil,  or for severe knock some  straight 70 oil,

try the 30 70 oil first, its only 25 £ a gall

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If you plan to drop the pan to check/change bearings (btw, it can be done with the engine in; awkward but doable), be sure to check crankshaft end float as well. I've seen big-bearing 1300s and 1500s with thrust washers in the pan -- just like some TR6 engines. This is not a good thing at all....

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Certainly possible in situ but fairly unpleasant and messy.  I did my Herald bearings in a London street once - and washed my hair with washing-up liquid afterwards!

'Tis a bit fiddly getting the sump past the chassis rail and no.1 BE is not the easiest to get at.  Worth checking the mains out while you are at it - the centre one especially gets tired and reduces oil pressure to 2 & 3 BE.  You may have to pass on the doing the front one though - that is a right sod to get at and is usually the least knackered......  Your knuckles, your choice!

My experience with 1500s is that you shouldn't let them knock for long - they tend to make themselves a new crank breather hole where the ful pump used to be....

Nick

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Howard81 wrote:
Has anyone done this before who can advise me on any tips and tricks?

Doesn't the front crossmember get in the way to make things awkward?


Yes, I have done this twice before, and the process is as I described in my post above. The cross member does get in the way but you just need to work round it. To make it slightly easier, do one bearing at a time, so that you can position the big end where you can get to it most easily, then turn the crank and do the next one, and so on.

It's not difficult, honestly - the first time I did it it took half a day. Second time (different car) it was only a couple of hours - no fuss at all. The only time issue is if you don't know what size bearings you want until you take an old one out. How about ordering std, .010, .020 from a supplier with the arrangement that you return the ones that you don't need?

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Drain the oil in advance, only a bit, it all helps. I remember lifting the engine a bit too. Again it all makes life a little easier. Twas a long time ago, so can't remember how I held it up. Probably involved blocks of wood or other cunning plan.
Main bearings are worth def doing if you feel up to it, the upper ones can be done in situ, just a little fiddly. You may want to do the thrusts too while in there. Again, only a bit extra and peace of mind.

When you do the job, be aware you WILL want to clean the inch or so of crud out of the sump.
And take care of those ali blocks at the front and back. Different length bolts in those.

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Yeah, I've done it a few times on the Herald... As Nick says, watch your knuckles. Also, a thin piece of sheet metal (which is spotlessly clean) the same width as the bearings is handy for tapping the mains in and out.

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ferny wrote:
Also, a thin piece of sheet metal (which is spotlessly clean) the same width as the bearings is handy for tapping the mains in and out.
you can also use a small self tapping screw, insert it in the crank oil way and rotate the crank in the direction of the bearing tabs and use it to push the upper shells out (and back in, in reverse) the screw need not be screwed in, but just fit the oil way, and be just high enough to hit the bearing shell and no higher

don't forget to take off the fan belt, as this holds the crank under tension and can make the upper bearings difficult to get out

mike

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This is impossible!  After 10 hours I only managed to get one bearing cap off and a trip to hospital after getting oil in my eye.

You just can't get enough force on the bearings to get the nuts undone in such a confined space.

The bearing cap I removed was #4 and was in perfect condition, as was the crank.  40 oversize.

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Sorry to hear the oil in the eye problem.  Maybe protective eye-ware would be a good idea.
Socket and extension should facilitate big end nut removal.
Number 3 likely to be the worn big end.
I've not tried to change bearings on a Spitfire with engine in car.  Much prefer to remove engine and work on bench.  Less likely to make mistakes or injure yourself.

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You doo have to pull a face , as it shows you actually trying !!!
they will come off, just you prob no using a long enough bar,

just thinking here, have you got a new filter on,or is it the old one,!! could be caked up, so running on by pass only, this will give low pressure,
also the PRV may have got crud stuck init,, worth a look at that too

Marcus

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Thing is, you simply can't get a long enough bar in under the car.  It's most definitely an engine-out job unless you have really small hands and the strength of Hercules.  Thing is, I don't have the room to do that here, as I don't have a usable garage..

It's getting all bolted back together again, so if it breaks oh well.

However, I've been talking to a friend about commissioning him to build a 1300 up for it, taking it back to the correct engine size.  Much prefer a 1300 in a Spitfire.  The 1500 he built for my Dolomite was lovely :)

The current engine is nasty in every way, so it probably is pretty much kippered..

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Come on guys someone down that way must be able to help this chap

Please be aware if some spitful person in the street you live in complains to the local council they will be all over you for working in the street spilling oil, etc. I know a mate who got fined in Coventry for the same thing. Green PC idiots  :-/

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Terror alert here!  If getting the nuts free is such an issue then getting them properly torqued up again is going to be impossible for our hapless friend.  As said above, he needs the warm arm of the group at this point.  Isn't htat why we're here?

Easy for me to say as I'm across the pond but I've rolled on lots of similar cases over the years.  Cuz I was there myself when I got the Spitty.... :o

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I am so lucky I have Triumph friends to help me out in fact they are what I consider to be real good friends Big thanks to you guys. I just wish I could help this guy out makes me feel bad he is stuck.

Just do'nt take any risks under that car on the side of the road make sure no fool runs over yor legs or anything.

Hey man good luck but when it gets on you wick just leave it and walk away and read the manual  :)

And before some smart gob says anything its not the drugs I am on I am just getting back to my old self.


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