Xantia Engine Banging

Vince B · Post by **Vince B** » 11 May 2005, 16:05

Two days ago I started off down the M4 yesterday with my Xantia sounding normal. After driving about a 35 miles -
clear run 70mph [;)] I arrived at our local town. In these town driving conditions I noticed a banging sound - started off quite but getting louder. Could have started off on the motorway but I didn't hear it as I had the radio on. When the engine is just ticking over the banging is low level, however I when I start to move off it gets louder and faster as I speed up and go through the gears. The nearest thing I can compare it to is when there is a problem with the exhaust, however I don't see any obvious signs of a problem here. I thought it might be a lack of oil, and sure enough the oil level was very low however I have topped it up but there is no change to the level of noise coming from the engine, if anything it is getting louder
Anyone got any ideas what might be wrong. I have a feeling this is going to be very bad news

arry_b · Post by **arry_b** » 11 May 2005, 16:16

Does the banging vary with road speed, or with engine speed. Does it get faster if you rev the car in neutral?
If it's engine speed related, you have a smoking gun already - you've been on a fast run on the motorway run with very little oil in the engine...
Cam damage?

jeremy · Post by **jeremy** » 11 May 2005, 16:19

Firstly how low was low?
Does the noise vary with temperature - ie does it make it when cold as well as hot?
How quickly does the oil pressure light go out? Does it come on at idle?
Is the noise like a hard thump, a rumble or a tap?
What engine is in your car, and what year is it?
Jeremy

Vince B · Post by **Vince B** » 11 May 2005, 16:47

Just answering two replys as once
The car is an 1995 2.0 petrol
The oil level was below the min level on the dip stick
It's a loud tapping sound which starts when the engine is turned on (cold) and continues when the it heats up. Gets louder when you rev the car in neutral. Varies with engine speed. Sound seems to be coming from the top of the engine (sorry not very technical)
Oil pressure light goes out as normal after starting (just a few seconds) does not stay on when the at idle. Didn't stay on when car had low oil level either [:(!]

AndersDK · Post by **AndersDK** » 11 May 2005, 17:10

The oil pressure lamp is not supposed to warn on a low oil level. It's more a <font color="red">"it's too late now mate"</font id="red"> warning.

arry_b · Post by **arry_b** » 11 May 2005, 17:27

Is the knocking at full engine speed, or half engine speed?

jeremy · Post by **jeremy** » 11 May 2005, 18:54

If the oil was a little below low and the oil pressure light didn't come on you probably haven't damaged the bottom end of the engine. This is supported by the fact it makes the noise when cold and that the oil pressure light doesn't come on at idle (assuming the idle is normal speed.)(If it does come on it doesn't mean the engine is wrecked and it may go on for many years like that but its an indication)
Does this engine have normal tappets or hydraulic ones? If it has hydraulic it sounds as though one may have been starved and damaged?
Jeremy

Mosser · Post by **Mosser** » 11 May 2005, 19:03

Can you do a recording of the noise and post an mp3 or wav of it?, it'll be much easier for us to diagnose then,
To me, it sounds like big end trouble and driving it will make it much worse, you need to get it looked at asap
I'm actually repairing an Alfa 156 that has a banging noise when running and increases as you rev it, and it is the no 4 journal and shells that are knackered, and i'm currently grinding them myself and its taking ages to do

rbruce1314 · Post by **rbruce1314** » 11 May 2005, 19:41

According to my sources the 2.0 petrol is notoriously weak on Bigend no4 and it can go even with such minor things as a thermostat jammed shut and overheating. the bigend noise on this vehicle sounds as if it is coming from the top of the engine. I know all this because it happened on my son's car!

ItDontGo · Post by **ItDontGo** » 11 May 2005, 22:03

1995 ZX. Not worth a bean really is it especially as you've knackered the donkey. I doubt its looked after if you ran it without any oil too so its not like 'better the devil you know' in this case. I think a new car is required personally rather than major engine work!

CommY · Post by **CommY** » 12 May 2005, 00:06

Mosser
re: the Alfa 156, the engines eat journals when wear on the crank bearings/journals has occoured as the bearing is all that keeps the crank true. You need to replace the crank bearings as well otherwise the crank float will make the problem re-occour rapidly. This problem often happens on badly maintained and thrashed (as all Alfa engines are) twin spark units that are loosing oil(maybe invisibly) via worn valve stem seals. The engine has a low capacity sump which doesn't help.
If you want info/forums on these blocks let me know. Though this is all probably old new to you.
You had to go and mention Alfa's on my Xantia forum didn't you[}:)]. A good women and a georgeos girl have a lot to answer to for[V].
Anyway lets stop talking about cars and get on with maintaining a exceptionaly comfotable mode of transport[:I]

Mosser · Post by **Mosser** » 12 May 2005, 05:32

Doh!, I have to do the crank bearings too ?, i have made a tool to regrind the journals without taking the crankshaft out, i cut the big end off a spare conrod, and sanded some shells down and glued sandpaper to the shells with silicone, and i bolt the whole contraption to the journal and spin it round and round till its down to .020 size, i find i can remove 0.02mm ever hour of work done, and have to remove 0.11mm left to remove, i got the ovality out of the journal and am just resizing it to fit the new shells at the moment,
Any help or sites to visit would be greatly appreciated as it taking way longer than i expected it to now,
Cheers

CommY · Post by **CommY** » 12 May 2005, 19:33

Mosser have you considered the block from a good 164(available for peanuts) or a wrecked 155. But watch out as the rebuild you are doing now is practically a service schedule item between 60-80k on a poorly maintained twinspark engine(80%).
I'm digging out the url's etc for you at the moment

CommY · Post by **CommY** » 12 May 2005, 19:51

Just read my replies and they don't make clear reading. I'm sure someone in the know alfa wise will explain it better. But the engines crank is a bit of a queer design which runs brilliantly till oil gets low then it eats itself. The crank is held true for end float purely by the bearings/washer/shims at each end. Once wear has happened the whole bottom end (bearings and shells/journals?) need replacing/fettling so the crank runs true again with the correct amount of float etc. and it will do this(run relyably while being constantly abused) with the correct amount of clean quality oil for 200K+. Let the oil slip and the engine is F-ed again. They have fixed this on more recent models by immobilsing the engine when a low oil level is detected(DON'T DISCONNECT YOUR OIL SENSOR AS IT COSTS) and only a main dealer can reset(expensive but saves the engine?!)