Weird 4age problems...

[skoty]

Driving the GT liftback home last nite when all of a sudden I hear a loud knocking/rattling sound coming from somewhere in the engine bay, I look down at the dash cluster and there are no warning lights displayed, as you do I was thinking WTF?

I was almost home so i pretty much rolled it into the driveway lol, turned it off and tryed to find out what had gone wrong. At first I thought something like a pulley or something external had come lose, but no so I checked the dipstick to ensure the dash oil warning light hadn't f**ked out and it was completly dry , yet the car had been running all day perfectly and had absolutly no signs of excessive friction or loss of performance! As there was no oil on the dipstick I assumed I had cooked something down the bottom end such as bearings, however apparantly on 4ages there is no reading on the dip stick till about 1.5 liters of oil right?

This began to confuse me as the car is making some weird knocking/rattling sound which sounds like its coming from under the cam covers somewhere yet there is no visual damage, however the car runs perfect, idols perfect yet makes weird noises as Ive damaged something. Ive checked a few external things and done a compression test, I got the following results:

Piston 1 - 160psi
Piston 2 - 175psi
Piston 3 - 175psi
Piston 4 - 170psi

Those figures seem fine to me but anyone please help, WTF has happened to my poor 4age??!!

[vvega]

have you tried filling it with oil and running it ???
note fill means topping it up not till it comes out the filler

if you ran it out of oil there prolly will be damage
but ya never know see what the top up dose

v

[skoty]

have you tried filling it with oil and running it ???
note fill means topping it up not till it comes out the filler

v

Yes, no need for the smart ass coments mate I sorta need to know if a minimum amount of oil on a 4age will provide enough lubrication to save the engine from crucial damage, btw I dont know where the oil disappeared to, it was apparantly done a week ago?!

[EVLGTZ]

check the waterpump, rattle may be coming from there.

[matt dunn]

with the key on and the engine off does the oil light work?

It may have got oil surge and run a bearing.

[lost]

I've got a 20valve silvertop, and mine did that about a month before the engine went. I still don't know what actually happened cause I never took it apart, but I turned it on one morning oil light on so i flicked it off straight away, dip in, no oil on it at all,so I was like wtf, but yea no loss in performance or anything prior to expect anything. I didn't have any rattling or what have you going on, but oil was just dissapearing, no leak, and wasnt burning it out the back, then bout a month later i boosted it in 1st, bang,lost 50% compression in cylinder 1. Still ran, though poorly as, with a loud ticking sound like something in the valvetrain was $&#$%, presumably a burnt valve. Not one of the 3 mechanics I took it to could explain why the oil was miraculously dissapearing in that month prior to it. I'd say the best thing would be to take apart the head and inspect shit before soemthing goes. Easier said than done though. All the best man

[skoty]

check the waterpump, rattle may be coming from there.

First thing I checked, btw its royces (fatke30) old gt liftback.

[skoty]

with the key on and the engine off does the oil light work?

Nope, thats what caused all this to happen, afterwards I noticed the wire had come off the oil pressure switch some how

[skoty]

BTW, if I have rooted a bottom end crank bearing, would the motor run as good as it does still? Most people believe thats what has happened but it just seems a bit weird, I thought the engine would idol irratically, struggle to turn over and have dramatically reduced performance also if that was the case?

[matt dunn]

BTW, if I have rooted a bottom end crank bearing, would the motor run as good as it does still? Most people believe thats what has happened but it just seems a bit weird, I thought the engine would idol irratically, struggle to turn over and have dramatically reduced performance also if that was the case?

There is a difference between running a bearing and seizing.
With a run bearing all you will notice is noise at first, untill it seizes later.

[RedMist]

I'd almost bet it's piston slap. Sounds very much like you have run a bearing.
Had exactly the same issue on my SW20. Ran it low on oil and a knocking sound started, filled it up and the noise only got louder as I continued to drive it. Your damaging pistons, bores and possibly head by running it, however it would be cheaper to replace the damaged engine than rebuild it!

Daniel.

[solberg Fan]

Drain the oil into a pan, check for metal shavings. If theres any there, id say you have a big problem on your hands Before you throw it away, take it to a mechanic, or better, an engine builder. They may be able to tell if its from the crank or bearings or what ever.
This hapened to my dad and the engine guy said it was probley from number 3 or 4 cylinder bearings (cos they are the last to get the oil feed).
Give it a go and hope for the best

[ants_ae92]

4ages are well known to burn oil when given a good thrashing! So let that be a lesson to everyone. Of course you wont see that it is burning oil becasue you wont be looking behind it when you thrash it up the road.

[Distrb]

I'd almost bet it's piston slap. Sounds very much like you have run a bearing.
Had exactly the same issue on my SW20. Ran it low on oil and a knocking sound started, filled it up and the noise only got louder as I continued to drive it. Your damaging pistons, bores and possibly head by running it, however it would be cheaper to replace the damaged engine than rebuild it!

Daniel.

i'll back daniel on this one...

had the same noise on my silvertop when it spat the dummy (but without the piston slap) sounds like the problem is in the head, but its not

[skoty]

-The noise sounds like its coming from the head?

-Will the compression test I did show if there is really bottom end damage, wont it just show top end damage if any?

-What should I do now? Basically is it just worth replacing the entire block with its components?

-If I have done major bottom-end damage is it possible for the metal shavings to have returned up to the head through the pump and causing yet more damage?

[skoty]

Anyone got a spare 4ag sitting in there garage?

[RedMist]

Piston slap can happen in one of either two ways. The tinny ring of loose fitting racing forged pistons when the motor is cold. The piston shakes in the bore and slaps off the sides of the cylinder. Always makes me cringe!

Or the piston hitting the head, with a damaged bearing the rod is able to move up the bore more than normal and the piston to slaps the head. (I'm probably wrong on this one, but it's the way I was lead to believe my problem)

[4ageman]

the 4age sump hold's 3 and a half litre's and from h to l on the dipstick is 1 litre. the l on the dipstick is the lowest point of the oil pump pick up. Ive done bearings twice now and it started of as a quite knock from the engine and just got worse.

[skoty]

Im afraid ive damaged more than bearings... I will take the sump off tomorrow and investigate, how hard is it to replace crank bearings and the cost of them. Is it best to use a dial gauge to check any distortion of the crank?

[ChaosAD]

Sounds like a 'Death Knock'.
If your keen, you could pull the big end bearings off and have a look, check the crank for wear. If the bearing hasnt spun and the cranks alright you may be able to replace them. Otherwise the engine needs a rebuild/replacement.