Is This A Head Gasket Problem

[ridway]

My galaxy 2.3 petrol (lpg conversion) has developed a tapping/popping noise from the rear of the engine. It sounds almost like a branch of the exhaust manifold leaking but thats at the front. If it was a leaking inlet manifold, Im I right in thinking it would be more of a hiss. I personally suspect it to be a head gasket or a valve/tappet problem. The engine runs smoothly but there is a very small hint of a cylinder that is not quite pulling its weight; this however may be me thinking to deep and imagining things. There is a coolant loss but it is very small. the coolant will drop until the warning light picks it up but this will take 3 to 4 thousand miles of hard driving in summer. A couple of tea mugs will bring it back to its normal level. The source of the noise as best i can tell is at the rear of the head (transverse) somewhere in the region of cylinder 4 if this is the one closest to the gearbox

 

Has anyone any thoughts or experienced this problem?

 

Rich, thanks in advance and a HNY

Edited January 1, 2009 by ridway

[Steve P]

I'm having exactly the same problem at the moment - and we have a 2.3 with LPG on it. I think this is just a co-incidence though.

 

Haven't noticed any water loss - I really hope there isn't any because then we may be looking at head gasket - which I really don't fancy doing at all.

 

I was thinking that it must be inlet manifold so I have got that off at the moment (that's a job and a half - ask if you need any tips!!!) Our LPG has backfired a number of times over the years ( it's one of the older single point injection systems) - wrecking the air filter housing and blowing various vac pipes off - so I was thinking that given it's a plastic manifold perhaps it's become cracked. There was quite a bit of noise coming from the back of the head - I'm sure I could hear the valves - there was a quite a tinny tapping noise. However there was also a much deeper noise harder to describe - a bit like a vac pump that you get hear on some diesels. All the noise was coming from the gearbox end of the engine - seemed to be round the back. So I was thinking that it was in fact the inlet valves I could hear and the deep noise was vacuum being pulled. The inlet tracts on these these are very long so if just one is leaking I suspect the "suck" would be more in time with the cylinder rather than being balanced across all 4 (unless I'm thinking too hard as well).

 

The inlet manifold doesn't have a gasket as such but uses shaped rubber rings to seal against the head - I was hoping that they've gone hard with age and stopped sealing. I'll be ringing frauds in the morning to see how much they cost - they look expensive - to be honest I couldn't see any evidence of leakage and you've set me thinking now. Perhaps I should have done a compression test first. I'll do that next if I don't fix it with new manifold gaskets - although I could do a cold check now before I start putting things back on.

 

The engine seemed reasonably smooth - perhaps a tad rough at idle but certainly nothing like when only running on 3 if a coil packs up. MPG seemed to be about normal. It's been like this for some months (doesn't get used that much) so I would have expected to notice water loss / water in the oil etc. I'll pull the plugs out as well. Have you any plans to do any investigation? Do have access to a sytem to do a pressure check on the coolant system to rule out head gasket - I know I can't do that myself.

 

Looks like we'll be comparing notes for a few days!!!!!!!!!!!!

 

Steve

[seatkid]

Just guessing - burnt valve seat or microcracking around valve seat. Try a cylinder compression test.

 

Or perhaps an injector problem (presume its sequential injection)

 

Whats it like on petrol? If its the same could be an small air leak on inlet manifold

Edited January 1, 2009 by seatkid

[Steve P]

Makes no odds whether it's on petrol or LPG - sounds about the same. My system is none sequential - hence the misfires we've had - suspect ridway's is newer so probably sequential.

 

I'll do a compression test tomorrow afternoon - haven't the faintest what figures to expect on a stone cold engine but will do a comparison across all four. If it is the head at least everything I have done so far is in the right direction- thankfully not bolted anything back on yet.

 

The inlet valves look ok - no evidence of overheating (using a mirror and torch peering down the inlet)- I know that's not worth much - but I did think to at least look.

 

I so hope i haven't got to take the head off!!!!!!

 

Steve

[ridway]

Thanks for the replies so far guys. I did suspect valve and/or seat problems but I suppose there is no way of telling without a comp test or head off. Could it be a weak or broken valve spring? The reason I ask this is because the noise suddenly appeared one evening; I suppose if a seat was burning this would be a progressive fault that slowly got worse. The fuel usage is realistically 27-28 lpg and 30-31 petrol doesnt seem that has changed although i dont drive it much unless we go to France and it is mainly used urban runs.

 

The LPG system is the later type (4 injectors) and has been faultless; still is. I have never experienced a backfire. It will be very interesting to see what Fords say and how you go on with the O rings. I have told the wife to drive carefully (low revs) because I plan to do the same as you shortly when the weather permits , if necessary taking off the head.

 

I will keep you posted with any developments

 

Rich

[Steve P]

Well I'll keep you posted - I've already started to take ours apart and my wife is asking when it will be fixed - it's her runabout.

 

I'm not expecting Ford to be able to comment at all - other than to tell me how much of a mortgage I need for the o rings! It's not as though as though I can let them listen to the noise now that I have it in bits - and TBH I have very little confidence in most garages - unless the fault is obvious or there is a fault code they just start changing bits without thinking too much.

 

I'll do a compression test tomorrow and advise.

 

Whilst I had the inlet manifold off I was thinking of upgrading to a sequential LPG front end. With this doubt over what the problem is I'll defer justifying that expenditure with the boss!!!

 

Steve

[Steve P]

One bit of info I forgot to add - which made me think leaking /broken inlet manifold.

 

Our lpg system works by filling the whole inlet manifold with gas. Wife had been complaining of a gas smell when sitting in traffic or when returning to the car - but only if had been running on LPG. I had ruled out a gas leak because switching the LPG off got rid of the smell. The main solenoid is under the bonnet and leak checking after there is easy - which I had done.

 

Added to the other symptoms I'd convinced myself it was an inlet manifold leak!!

 

Steve

[ridway]

Im now even more confused but perhaps slightly happier. Got in the gal this morning to run daughter to a sleep over, when I got back the popping/tappity noise had gone , completly?!. The engine was dead smooth! Looking perplexed I reved it a couple of times and it was perfect. Just about to put the lid down and switch off and away it went again. Intermitently and totally random, irrelevent to the revs, although quieter at raised engine revs.

 

I'm now thinking along the lines of a sticking air valve or NRV or something of that nature. Not yet got the tis disk out yet but certainly need to look. Could you have a similar problem? At least now I know it isnt a burnt valve problem although I suppose it could be a valve spring or sticky valve. Tentatively I feel confident this could be the problem as the vehicle has only been used on short runs for the last year and it is well overdue for an oil change. So could a valve be gummed up/sticky, especially during this cold weather?

 

I'll let you know how things develop.

 

Rich

Edited January 3, 2009 by ridway

[ridway]

Update to last post. Neighbour of mine has just witnessed the intermitent noise. He has recently retired as workshop manager at a stealership. He is convincd the noise is a tappet problem. Apparently they are hydraulic tappets and he suspects that one is not filling with oil correctly probably a grain of "crud" or dirt stopping it filling up right. He says is first action would be an oil change and a good long high speed run up the motorway. Keep you posted

 

Rich

[Steve P]

Well - I've fixed mine today - and it was along the lines of what I originally thought. There was an air leak at the inlet manifold. As well as letting a small amount of air in at higher vacuum conditions - e.g at idle - this was clearly causing the noise (including probably letting valve noise out!)

 

I have isolated the leak to the rubber o rings (although they are not actually O's). I did this because when I went to order some new ones (about

[ridway]

Things seem to move fast here. My optimism has died tonight fetching daughter back from work, whereas am pleased you seem to have solved the problem.

 

Driving back the old gal started firing on three cylinders; badly. It is also back firing and I could smell gas or petrol depending which is selected. The popping noise has increased by several decibels really does sound like an exhaust manifold branch hole or gasket but it isn't. I suppose the evidence for that is where the noise comes from and the fact that if it were the exhaust side the noise would really get louder if reved; it didnt. Now depressed I'm torn between a severe inlet leak or what my neighbour said about the valve tappet. Because it ran smoothly today and from what you have disclosed (Steve P) I'm still with manifold leak. Why would I smell gas or petrol so much with a burnt valve seat or sticking inlet valve? It is almost as though the rubber seals you talk about have given but because its a vacuum it temporily resealed itself this afternoon but this evening has given way completly leaving part of the manifold open to atmosphere. Having no idea what the manifold looks like yet, are they seperate tubes or a common plenum chamber? Does this sound feasible Steve knowing what you have found?

 

One other thing I notice was that for a brief momment the ECU warning (the engine icon) light flickered for a few times but then went out again as we continued. I think this may have been the back fire upsetting the MAF or Oxy sensor? My daughters comment was "Dad the engine sounds as though its going to blow up but at least you know the warning light works". Are'nt they helpful? The gal got us home but is now sat all looking sorry for itself on the drive a bit like me.

 

Any advice welcome from anyone, particularly from Stevey P as you've had first hand experience.

 

Rich

Edited January 4, 2009 by ridway

[sepulchrave]

I think you can now discount the tappet ridway, there is no way it would cause a malfunction that bad.

 

Can it be a faulty coil pack, have you identified the cylinder which is playing up and tried swapping with a good cylinder, have you checked your spark plugs?

 

Spark plug colour is an excellent diagnostic tool particularly for gasket leaks and burnt/sticking valves.

 

A compression test will reveal if you have burnt or sticking valves so stop guessing and start testing. You must be methodical with fault diagnosis and not exclude any possibilities until you've tested for them.

 

All we can do on the forum here is make educated guesses and try and narrow things down for you but you can waste days with bad advice and red herrings so be careful not to clutch at straws.

[ridway]

Hi sepulcharave

 

You are right I now need to get my hands dirty and tackle the problem. Luckily the gal is not my primary car so there isnt a great urgency but it still needs fixing soon.

 

I agree with you having slept on the problem that it cant be a tappet now so Im off to get long inspection mirror and have a look this afternoon at the integrity of the inlet manifold prior to getting the tools out.

 

Thanks for the guidance, I'll keep you posted on what I find

 

Rich

Edited January 4, 2009 by ridway

[Steve P]

There is no doubt you have got to do something - you can't keep driving now?

 

Comments.

 

Gas - smell - this could be gas leaking out of the inlet manifold. This shows up at idle and low speed. At higher speeds the airflow through the engine bay probably washes any spare gas away.

 

Size of leak. Typically we are talking VERY small leaks to have a noticeable effect. In the past if ours has back fired it has tended to blow a vac pipe off or a blank off the top of the manifold. This has a huge effect - and we are only talking 1/4 inch dia. The engine struggles to idle and is very lumpy - you have to rev it when coming to a stop or let it cut out then restart when you want to go again? Also when it's doing this other things happen - like the cat gets red hot and starts to smell quite bad - probably because it is running so rough there is a lot of unburnt fuel in the exhaust. It could be that you now have two problems - the first caused the engine to run weak and misfire - which has then blown a pipe /cap off making it now run very rough.

 

I would say that the leak that I have just fixed on mine was only thou's wide and over about a one inch length on two of the o rings - not much at all. You wont see it with an inspection mirror -I doubt that you would be able to see it if you had the head and manifold on a bench in front of you. I could only JUST tell there was probably a leak once the manifold was off by inpecting the head with the mirror and strong light and looking at the O ring witness mark.

 

The inspection mirror is used to help see the back of the head for locating bolts/pipes / connectors etc.

 

If a coil pack has given up this is best investigated with a spare set of ignition leads - lift the coil packs off the head and fit the leads in between the packs and the plugs. You can then do checks such as pulling off one lead at a time to see if it makes a difference. If it does - move on to the next plug - if not check to see if the coil is giving a spark. You might find one plug smells of petrol if it's not working at all.

 

Compression Tests - I agree this can show faults but only bad ones. I did test mine while I had it in bits - results were 210/185/210/210. I could have got excited about the 185 - haynes suggested this MIGHT be a worn cam lobe. To be honest it could be lots of things. 185 is a reasonable figure on a cold engine so rather than take the cam cover off (which I was contemplating) I decided to press on and ignore it for now. Wise decision with hindsight. It might be showing some other underlying problem but the thing is running so sweet now I'll investigate if it causes a problem - might repeat the check with a hot engine.

 

Plug colour - again can show bad problems isolated to one cylinder - but depends how bad it is. Mine all looked a little weak but nothing to write home about. I would say that I could not tell which ports had been leaking (unless they all were!).

 

Good luck!!

 

 

Steve

[ridway]

Good news but the plot thickens.

 

Thankfully I've found the problem now I finally decided to brave the cold weather and get my hands dirty. Would you believe a No3 spark plug had come out? Took off the centre cover and there it was just sat in the hole attached to the HT lead. A new plug (as the bottom 2 threads were damaged) fitted and TIGHTENED and it is now as sound as a pound; I'm really chuffed.

 

It was obvious the plug was not tightened from last attended (the other three are) to, I must have been was responsible for that because I do all the work on it. The puzzle is how has it managed to do 16000 mile with a plug that was only screwed in possibly 2 or 3 turns with out so much as a misfire? It has certainly not worked loose because the HT rubber shroud and cable were well stuck to plug insulator and there is no way of it twisting perhaps 20 or 30 turns to wind itself out.

 

Anyway, Im pleased it works now, repremanded myself for bad workshop practice, but puzzled how it ran to Spain and back in that state plus a years motoring. Sincere thanks for all the help and encouragement from you guys that contributed to the thread.

 

Although everything is running fine now the incident has left me with an ECU light lit on the dash. Is there a simple way to clear this or do I need a diagnostic machine thingy? I am sure it logged a fault because when it was backfiring it was trying to eject the loose sparkplug out the head. The backfire obviously stopped because the plug gap had disapeared (short circuit) when it kept falling back down the hole, either catching the side or from the force of the fuel exploding or the plastic cable support which broke up at the bottom. I manage to limp home on three cylinders with no more back fires after the first few.

 

Happy New Year

 

Rich

Edited January 5, 2009 by ridway

[ridway]

Fault light on the dash for the engine has now cleared. Suppose the ECU is clever enough to see the problem has gone away.

 

Rich