Glowing exhaust manifold question
Discussion
Just gave my car its weekly run up as its bagged up for the winter. Started making an odd faint whirring noise so I popped bonnet. Garage lights were off, but was rather alarmed to notice the 2nd from rear(passanger side) exhaust port was glowing a dull red. I know things get a bit hot under there, but is this normal? All others wee normal clour. Cant say I have ever seen that before. A long time ago my mates mini suffered from a slipped exhaust manifold gasket that caused a blockage and his was glowing bright orange, wondering if a similar thing has happened.
I'm not overly concerned for now as its off the road, so will get it looked at in the spring if need be, good oppurtunity to replace gaskets and remove pre cats anyhow I was thinking.
Anyone throw some light on it?
I'm not overly concerned for now as its off the road, so will get it looked at in the spring if need be, good oppurtunity to replace gaskets and remove pre cats anyhow I was thinking.
Anyone throw some light on it?
zippy500 said:
is this normal?
No. It's normal for the exhaust headers to glow at all unless the engine is highly tuned and on full load, and it's also not normal for just one header to glow. It suggests there's something wrong with that cylinder, perhaps a misfire or poor combustion allowing unburned mixture into the exhaust.Had another investigate of this and it looks as if the 2 right hand side rear headers are glowing a tad, more under load as you would expect. All other headers are fine. This was done in the dark so they are not molten steel or anything, just a faint orangey tinge to them with the lights off.
So looking like what ever is happening is affecting the back two cylinders, right hand bank only. I still would like to believe its something to do with the manifold gasket being shot.
I take it each injector is individually fed info by the ECU?
Wondering if they are being overfuelled due to an exhaust leak or something?? Seems they use the same gasket.
Cant see any visable signs of one, but could be a tiny one underneath as I do have a ticking noise when I listen.
So looking like what ever is happening is affecting the back two cylinders, right hand bank only. I still would like to believe its something to do with the manifold gasket being shot.
I take it each injector is individually fed info by the ECU?
Wondering if they are being overfuelled due to an exhaust leak or something?? Seems they use the same gasket.
Cant see any visable signs of one, but could be a tiny one underneath as I do have a ticking noise when I listen.
Hmm, can see this is gonna be an interesting investigation.
Just had a chat with Neil Garner so am now armed with a few checks to do before bits need to come off. Namely compression test, check plugs etc.
Just need to find the time to do it all :-)
He seemd to think it wasnt anything to do with the gaskets, so will forget about that daft idea of mine.
Just had a chat with Neil Garner so am now armed with a few checks to do before bits need to come off. Namely compression test, check plugs etc.
Just need to find the time to do it all :-)
He seemd to think it wasnt anything to do with the gaskets, so will forget about that daft idea of mine.
Hi,
I have had something similar, noticed my manifolds were glowing a very dull red - at night time away from any light source, in daylight it could not be seen. Some manifold tubes were brighter than others after. After a cam change the glow was still there but the same intensity on all tubes. At night some where dark hold the revs at 2000 - 3000 rpm for 30 seconds then check your manifolds - they will be glowing.
ozstyle
I have had something similar, noticed my manifolds were glowing a very dull red - at night time away from any light source, in daylight it could not be seen. Some manifold tubes were brighter than others after. After a cam change the glow was still there but the same intensity on all tubes. At night some where dark hold the revs at 2000 - 3000 rpm for 30 seconds then check your manifolds - they will be glowing.
ozstyle
If the glow is fairly even across the manifold then that would indicate a 'normal' combustion process, I think what GreenV8S if refering to is if only one manifold tube is glowing then that would not be normal i.e. there is a fault.
You have to remember the exhaust gases coming out of the cylinder head may be up to 1000C or more on the highly tuned ported engines....marshmellows anyone
Bodders
You have to remember the exhaust gases coming out of the cylinder head may be up to 1000C or more on the highly tuned ported engines....marshmellows anyone
Bodders
spend said:
Take your precats out, they are possibly blocking the flow.
Yes i have heard of a blocked pre cat causing this so I concur with Scruff Bag !In fact take them out anyway as you do not need them to pass an MOT and it will reduce under bonnet temperatures significantly as well as three or so extra HP and a better sounding exhaust note
This could be the start of a new winter craze ... revving the nuts off the Griff while in the garage just to get a better "glow" than anyone else.
ok ... we all need to go out & buy a Infrared Thermometer then start a new forum with our scores. Just need to pick a night with the missus out to WI.
ok ... we all need to go out & buy a Infrared Thermometer then start a new forum with our scores. Just need to pick a night with the missus out to WI.
zippy500 said:
I take it each injector is individually fed info by the ECU?
Wondering if they are being overfuelled due to an exhaust leak or something?? Seems they use the same gasket.
If its the original prince of darkness ecu - its batch fired. So all the injectors on one side are fired together.Wondering if they are being overfuelled due to an exhaust leak or something?? Seems they use the same gasket.
Well, pictures were rubbish as I only have a phone camera, so gave up on that.
However, the plot thickens now, held it at about 2k for 30 secs, and all 4 were glowing on one side. back 2 orange and one on the driver side was also a dull red. So I think its either running to lean or its a "They all do that Sir, now piss off and stop fussing"
Dont know if this is related. But In mid september I had the timing checked at Garners and it was 5 deg's advanced so it was reset and car felt much better to drive.
Was wondering could the ECU be just adjusting itself still as I have done literally 30 miles since this was done. Sure I read somewhere it takes 200 miles or so to compensate for any big changes. I have a vivid imagination so could have made thi sup.
However, the plot thickens now, held it at about 2k for 30 secs, and all 4 were glowing on one side. back 2 orange and one on the driver side was also a dull red. So I think its either running to lean or its a "They all do that Sir, now piss off and stop fussing"
Dont know if this is related. But In mid september I had the timing checked at Garners and it was 5 deg's advanced so it was reset and car felt much better to drive.
Was wondering could the ECU be just adjusting itself still as I have done literally 30 miles since this was done. Sure I read somewhere it takes 200 miles or so to compensate for any big changes. I have a vivid imagination so could have made thi sup.
my manifolds glowed, ma said take a fire extinguisher and drive it to TVR power, Power said do not drive it!!! Lost compression and Taraka 2 done and charged again. this year lost oil pressure , not charged any money but the car will not start on delivery back to me. Apparently cam bearing spun!! If I could only !!!!!!!!!!
zippy500 said:
Was wondering could the ECU be just adjusting itself still as I have done literally 30 miles since this was done. Sure I read somewhere it takes 200 miles or so to compensate for any big changes. I have a vivid imagination so could have made thi sup.
Adjusting what? - The ignition? - No. Also prince of darkness and clockwork.At idle, the exhaust manifolds should not be glowing if everything is normal. The exhaust gas temperature in this condition will be around 220 Degrees Centigrade, which is not enough to make them glow.
It is more disturbing that the glowing is not even on all cylinders. The only reason for glowing at idle (assuming that the car seems to be running without misfiring) is that there is mixture burning in the exhaust, because combustion has not completed in the chamber.
Possible causes for this are retarded ignition timing, faulty ignition amplifier or burnt exhaust valves amongst others. I notice you mention that you have checked the ignition timing, but it is also worth checking that the timing marks are in the right place! Compression and leak down tests should reveal any burnt valves.
A weak mixture can cause this, but only after it is so weak that the engine will be heard to misfire.
Manifold glow at higher revs is less unusual, depending on how brightly they glow. This again can be related to ignition timing (on a healthy engine), or the vacuum advance system not operating.
If a pre-cat is blocked, the glow begins at the engine side of the pre-cat, and spreads back towards the engine. Any blockage in the exhaust will always cause a hot spot.
It is more disturbing that the glowing is not even on all cylinders. The only reason for glowing at idle (assuming that the car seems to be running without misfiring) is that there is mixture burning in the exhaust, because combustion has not completed in the chamber.
Possible causes for this are retarded ignition timing, faulty ignition amplifier or burnt exhaust valves amongst others. I notice you mention that you have checked the ignition timing, but it is also worth checking that the timing marks are in the right place! Compression and leak down tests should reveal any burnt valves.
A weak mixture can cause this, but only after it is so weak that the engine will be heard to misfire.
Manifold glow at higher revs is less unusual, depending on how brightly they glow. This again can be related to ignition timing (on a healthy engine), or the vacuum advance system not operating.
If a pre-cat is blocked, the glow begins at the engine side of the pre-cat, and spreads back towards the engine. Any blockage in the exhaust will always cause a hot spot.
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