Home › Forums › Stay Dirty Lounge › Service and Repair Questions Answered Here › What do you make of this noise?
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August 14, 2014 at 9:58 pm #612840
Hi guys,
I’m new here so please forgive me if I am posting in the wrong place.
My Renault Laguna 1.9dci dispensed all it’s coolant, overheated and shut-down while away on holiday. There was a fair bit of oil smoke from the engine, but the oil level was good. Although the engine had stopped from overheating it started again when cool and I drove gently to a local garage and got the coolant fixed then drove home (300 miles).
Now the car has a clacking sound when cold which mostly goes away when warm. I’ve refreshed the oil since it was smelling burnt but the sound remains much the same.
What do you experts think about this sound? Could it be a ‘big end bearing’? It sounds like it comes from near the bottom of the engine but I could be wrong it’s hard to tell.
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August 14, 2014 at 10:23 pm #612844
Hello, my first impression from what you are describing alone is that you blew a head gasket. Losing all the coolant like that could either be a cracked radiator, or a failure in your cooling system at the head or water pump (most likely spots). With you additionally mentioning that you are getting smoke, that is either coolant on the engine or coolant in the cylinders themselves. Is the smoke under the hood or from the exhaust pipe?
Again my first impression is your head gasket blew. I can’t listen to the noise at this moment so I can’t be much more help…. I’m sure more folks will chime in.
Good Luck
August 14, 2014 at 10:42 pm #612850Thank you for your quick reply.
I should have been more clear; the coolant issue was solved it was a burst pipe, simple as that. However there is obviously some wear from the experience.
August 15, 2014 at 12:21 am #612862On older engines I could tell the difference between valve and rod noise. On new motors they sound the same to me.
August 15, 2014 at 12:45 am #612867Let me get a few questions out of the way that may help with a resolution.
First, you stated that the engine stopped, was this because you pulled over and turned it off, or did the engines computer turn it off because it was overheating?
Second, you said there was oil smoke, so oil had to get out of the engine somehow… where would oil come out of on your specific engine that would cause it to smoke… could be the pan gasket, possibly hitting the exhaust, could be the intake or head gaskets and hitting the block Could be a number of things. Does your car currently leak any oil externally? When you changed your oil, did you see if there was any radiator fluid in it? Do you have oil in your radiator?
Was your oil smoke under the hood or from the back of the car?
Have you checked anything around this burst “pipe” that could have possibly been injured by the burst? I’m thinking belts, fanshroud, fanblades, things that move and can make noise.
August 15, 2014 at 1:18 am #612871Hi,
Good questions. The engine stopped itself when it overheated. I’m not sure if the ECU stopped it (I hope so) or the engine just stalled from the friction. As there was no water in the system the coolant temp gauge showed a reasonable temperature.
The oil vapour was directly after the overheat from under the bonnet, there is none now the coolant system is repaired. It is hard to say where it was coming from but I think mostly caused by vapour from the oil condenser that then feeds oil vapour it can’t condense into the air inlet pipe, through turbo, intercooler and to the inlet manifold. All of this had oil on it after overheating. When I took the air inlet pipe off the manifold there was vapour coming out the inlet manifold on the top of the engine so the top of the engine was obviously very hot indeed.
However, I don’t think this clacking sound was quite so apparent until after the 300 mile drive home on thin oil following the overheat and coolant system repair. I’m thinking something was stressed by the overheat then worn even more by running for a long time on thin burnt oil.. but just what part is worn I don’t know?
The coolant from the burst pipe just fell down the back of the engine on the block and a little on some other pipes engine mount etc.. nothing to make a clacking sound I think. I don’t see any oil vapour or smoke from the engine now and on the drive home I was getting good economy as high as 62mpg, I just have this remaining noise.
August 15, 2014 at 1:23 am #612873Do you know if your turbo is cooled with engine oil or coolant? I know nothing about these cars but I think basic mechanics will still apply.
August 15, 2014 at 2:37 am #612889I already mentioned two possibilities. A third is an exhaust manifold leak.
If no exhaust leaks then I would suggest pulling the pan and checking for any loose or discolored crank/rod journals. I don’t know what sort of valve adjusting system this vehicle has but if hydraulic, that is the third possibility.
August 16, 2014 at 3:03 am #613078Anytime you overheat an engine to to point of seizure, it causes damage. The extent of the damage is impossible to determine until you disassemble the engine. It’s normally global and not particular to any one part. What happens is that there is soo much friction, the metal parts expand to the point where they can no longer move.
I will say this, engines that suffer that fate are often on borrowed time. How much time depends on the extent of the damage. As stated, that damage cannot be determined without some exploratory surgery. If you do find that the engine is damaged beyond repair, I would recommend replacement over rebuilding. I explain my reasoning for this in this video.
Good luck and keep us posted.
August 16, 2014 at 6:55 am #613120[quote=”Tenson” post=107966]Hi guys,
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Now the car has a clacking sound when cold which mostly goes away when warm. I’ve refreshed the oil since it was smelling burnt but the sound remains much the same.
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Is this the case indeed? As it awfully sounds like GM piston slap. That goes away as engine warms up. So your engine overheated, and engine block warped a little bit. Causing piston slap.
And for the sake of automotive gods, please, do NOT rev that engine until noise goes away.
If this is the case, that it goes away, you either drive on it as is, as I did on my Silverado for about 60 K miles, and sold as is, or, you have to pull engine, re-machine piston bores, and get her all new pistons and rings. Is she worth this?August 16, 2014 at 8:39 am #613135[quote=”Tenson” post=107971]Thank you for your quick reply.
I should have been more clear; the coolant issue was solved it was a burst pipe, simple as that. However there is obviously some wear from the experience.[/quote]
=====================================================+1 on Erics comment above of course.
There was a risk of significant damage when the coolant was discharged and only the oil was left to dissipate the heat. Then the oil, circulating through the engine to lubricate, gets to extreme temperatures. The motor oil remaining in the system then becomes thicker and heavier and with the thickening effect of the extreme heated oil you get lubricant that is harder to pump, poor oil circulation, less heat dissipation and increased engine wear.
The worst thing you could have done(as mentioned in your post) is to then restart the engine when cold and drive the vehicle with no coolant. The engine heats up very rapidly and only the oil is left to cool the metal parts. You will have potentially caused greater engine damage by doing this.
This is very unfortunate story but is a good reason for owners to change their radiator hoses at least every 5-6 years whether or not it appears they are degrading. Just have it done at the same time as you have a scheduled coolant change. They are so inexpensive to replace but the major damage that can be caused by failing to do this, and then having a hose blow, can potentially be very costly.
August 16, 2014 at 7:54 pm #613199If the noise was not there before the overheat and by listening to the sound I suspect that you have some internal damage inside. Sounds to me like a piston noise and as Eric explained there is no way of knowing how much without disassembly and inspection.
That said, it’s possible that you could drive the car for years without a problem as long as the noise goes away when the engine is heated up and you drive it easy when the engine is cold.
If it gets worse then you will need to deal with it.
August 28, 2014 at 9:08 pm #616616I’m going to try changing the tappets. One has a slightly larger gap than the others between it and the cam (about 5 thou bigger). The others have some wear marks too. I need to do the timing belt and coolant pump anyway.
I figure given the speed of the noise it is most likely a tappet because in that video the engine was idling at 800RPM so if it were on the crank that would have a repetition of around 12hz. If it were a piston it would either be about 12Hz if it made the noise going up and down or if it were only in one direction of the stroke it would be about 6Hz. In this case I think the noise is more like 3Hz so I am thinking it is a tappet. Does that make sense?
August 30, 2014 at 3:22 am #616974I’m guessing most of you will not have had the chance to see many European engines so here are some images of working on my engine (1.9L diesel turbo) to change the tappets / cam follower buckets. It’s a single overhead cam. Basically cambelt off, water pup out, belt tensioner out (changing both), engine mount off, fuel pump off, vacuum pump off, cam-shaft cap beam off, camshaft out, tappets out.
August 30, 2014 at 9:31 am #617033I’m loving that water pump. That’s the way they all should look.
September 10, 2014 at 1:23 am #619568Engine reassembled with new tappets shimmed to the cam. Cam checked for bearing ware. New water-pump, cam belt, drive belt and engine mount.
The sound remains. I’m not sad I did the work because the cam belt I removed had a tooth starting to brake off so I might have saved myself a catastrophe there. Also pulling away in first gear is much smoother now the worn engine mount has been replaced. Car drives wonderfully now… except the annoying tapping / clicking sound from cold.
So I’m starting to think it may well be piston slap as suspected by a couple of you earlier. Prior to giving up though, I will try to remove my injectors (always really stuck in!) and see if that is the cause. If the problem is piston slap I’ve got a tin of Ametech Engine Restore to use which I have heard very positive things about.
I need to correct myself earlier too. I said that if the noise was piston then it would be at the speed of engine rotation (about 13Hz ) but it may be the piston slap only occurs on the combustion stroke which would make it sound slower.
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