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Exhaust Manifold Red Hot

Discussion in '308/328' started by motionbroker, Oct 2, 2009.

  1. motionbroker

    motionbroker Rookie

    Feb 29, 2008
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    #1 motionbroker, Oct 2, 2009
    Last edited by a moderator: Sep 7, 2017
    Im trying to help out a friend in Bangkok by posting for him.

    Below you will see pics of the rear exhaust manifold on a US spec 85 qv. After 20-30 minutes of operation the manifold is glowing red hot and as you can see it has started to melt. We assume the forward manifold has the same issue but we cant see it easily.

    They have checked the obvious causes for this problem. The valves have been checked and the fuel system is in great shape. In fact the car is running extremely smooth so we are mystified as to what would be causing the problem.

    Anyone out there seen a similar issue? Obviously anything getting this hot is pretty scary and a big risk for fire etc so we really want to get it sorted out.

    Thanks in advance.
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  3. CliffBeer

    CliffBeer Formula 3

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    Have you checked to make sure you don't have a partially blocked cat?

    And, all four cylinders on the rear bank are firing correctly? It only takes one non-firing cylinder to put a fair amount of gas into the manifold and cats.
     
  4. davebdave

    davebdave Formula 3
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    Water Pump?
     
  5. st@ven

    st@ven F1 Rookie
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    maybe you checked the valveclearance but dit you check exhaust timing of the particular bank? wrong timing can lead to this too.
     
  6. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    It's very important to determine if the 5-8 manifold has the same problem as the 1-4 manifold, or not, in terms of deciding where the trouble might be (i.e., some problems can only affect both banks -- so, if only the 1-4 bank manifold is running red hot, those possibilities can be eliminated, and only those things that can affect a single bank need to be investigated).

    Does the car have a catalytic converter? If so, when the manifold(s) are red hot is the catalytic converter also red hot?

    (Assuming that both manifolds are running hot) one easy thing to try is unplugging the O2 sensor from the injection ECU and seeing if that makes any difference.
     
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  8. AZDoug

    AZDoug Formula 3

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    #6 AZDoug, Oct 2, 2009
    Last edited: Oct 2, 2009
    If it one bank only, I would look at retarded ignition timing first, if the car has two distributors. A sticky/binding advance mechanism could cause this if these distribs have a mechanical advance in this particular car.

    Doiug
     
  9. mike996

    mike996 F1 Veteran

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    Agree with Doug - check timing. I've seen this in US cars. If the Ferrari has 2 dizzys, one of them could be badly mistimed while the other is not.
     
  10. PhilB

    PhilB Formula 3
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    #8 PhilB, Oct 2, 2009
    Last edited: Oct 2, 2009
    Maybe it's me but the manifold doesn't appear red hot, it appears to be painted a rather ugly brown. Note the paint chip, and the paint scratch. Also note that bolts are being used to plug up the exhaust analyzer tube connections, and the bolts are painted this cr@p brown color as well. Copy it into an image viewer and zoom in to take note.

    OP says it's a US spec 85, the photo then clearly shows that some of the emission equipment was removed and the manifold was at one time removed from the car. Probably a number of things wrong with the car then.

    The manifold also doesn't appear to be melting, but rather the insulation baffle (remember, it's a US spec car) appears to be dented - said dent probably occurring when the manifold was removed/reinstalled during the above mentioned painting procedure.

    One last note. OP says owner assumes front manifold is glowing red hot as well. If that were the case, I'd bet money the car would self ignite - a glowing red US spec manifold means a temp of what, around 1800-2000F degrees, and at 4 inches from the gas tank....nah I say, most likely more brown paint applied to the forward manifold.

    Or maybe I'm blind.....
    Phil
     
  11. 308nut

    308nut Formula 3
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    #9 308nut, Oct 2, 2009
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    I'd have to agree with PhilB, that looks like it is painted, also, that is the heat shield, normally you would not see the glow of the pipes transfer to the heat shield where it would be that noticable.

    Now this is a glowing exhaust manifold


    Wade
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  13. mike996

    mike996 F1 Veteran

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    Well...I ASSUMED that if the owner said it was glowing red hot, then it was. But, as noted, if it's NOT glowing red hot then any diagnosis can't be much good if the symptoms are not correctly described.

    So does the manifold get red hot or not?
     
  14. PhilB

    PhilB Formula 3
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    Unknown.


    But I just can't get past that brown....

    ...why....

    ...it's just wrong.


    I'll tell you, I bet whatever spit out that brown glowed red hot.

    ;-)

    (Sorry, but I had to say it.)


    motionbroker - if you or your friend really needs help, post the same photo of the manifold after the car has been running about 20-30 minutes. Also, since the exhaust analyzer pipes are missing, maybe you can have your friend take a look to see what else is missing (US spec cars have a single catalytic converter, maybe it was removed also). And - VERY CAREFULLY, use a cell fon/bb camera (since they are small and flat) to take a photo of the front manifold after the car was running 20-30 minutes.

    Phil
     
  15. thecarreaper

    thecarreaper F1 World Champ
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    to try to help you : the answer is no, it should never get hot enough to change color if the car is running properly. if it is in fact running that hot, then there would be a intense fuel smell behind the car, and it would not run smoothly. i would make sure the front bank does not have a problem. fire is the biggest killer of these cars.
     
  16. motionbroker

    motionbroker Rookie

    Feb 29, 2008
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    Thanks to all for your responses

    Clarifications below:

    1) The mechanic confirmed this morning that both manifolds (1-4 and 5-8) have the same issue.

    2) Yes I realise there is crappy brown paint but this mechanic is very good, and if he says its glowing red hot I believe him. This picture was taken when the engine was cold.

    3) the car has had the catalytic converter removed. I am not sure about other emissions control equipment. I will check with the owner later today.

    Really appreciate the input.

    Dennis
     
  17. motionbroker

    motionbroker Rookie

    Feb 29, 2008
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    so based on the clarification above anyone have any ideas?

    Thanks,
    Dennis
     
  18. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    You were going to give some more information -- e.g.,:

    Does it still have the air injection system? (Doesn't look like it in the picture)

    Does it still have an O2 sensor?
     
  19. ramosel

    ramosel Formula 3

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    You say its running fine - we'll have to assume it is.
    You say the fuel system is ok - how have you ascertained this? tail pipe sniff? (May be overly rich)
    Is it noisy (exhaust)? - may be a broken weld or pipe inside the temp sheild allowing hot exhaust gases under the temp sheild?
    Are both the heat sheilds consistently brown all over? could be they were painted black at one time (I've seen that) and its just burned down to brown. I know, that doesn't account for the glowing red but would account for the consistent brown afterwards?
    If the cats were removed, it may be because they were blown out and all the contents are now blocking your mufflers, that would create back pressure and your red hot exhaust... but it wouldn't really run well. Have you another muffler to test with? Take that one off and check it?

    Just some ideas.
    Rick
     
  20. Jbryant

    Jbryant Karting

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    Well,
    I have seen this also. There is a crack in the heat shield of my 308 GTSI. At night, after a good run, if I open the hood and look down at 1-4, I see the exhaust pipe glowing. The car is running great and If I run it hard, it runs like a bat out of He##.

    I have always just assumed it was OK like that. Never really had a concern. I replaced the CATS a few years ago with Hyper-Flows and nothing looked to be out of the norm.....

    I am thinking of using that High Temp Exhaust Rap material and get rid of the heat shield. The shield is not in good repair and I used this rap material before on a 327 and 396 and it worked really great.

    .02c worth
     
  21. jgoodman

    jgoodman F1 Rookie
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    #18 jgoodman, Oct 8, 2009
    Last edited: Oct 8, 2009
    That picture is unbelievable! How long and how hard was that engine running?
     
  22. climb

    climb F1 Rookie

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    #19 climb, Oct 8, 2009
    Last edited: Oct 8, 2009
    My 1980 308 gtsi does that too.

    At idle it doesn't glow but when i pull it in after a good run i can see the glow through the little holes in the head shield. I'm sick of freaking out about it. I've replaced and cleaned and grounded everything i can but it still glows.

    You car has electronic ignition and still does it so my idea of fixing it with Nicks ignition is blown to hell.

    I wonder if the manifold/valve problems on the 355/456/360 etc. are manifestations of Ferrari not getting the fuel delivery right. May have the same condition on the 308 but without the same degree of damage because of the lower compression/performance. It would explain alot of the fires too.
     
  23. Nick

    Nick Formula Junior
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    It's a timing issue, if the exhaust is not plugged & you have no cats, it is that simple from my experience with 308’s. My direct coil system fixes that issue, the problem is in those digiplex boxes, you have one for each bank of cylinders in all injected 2 & 4 valve 308's they are all getting old now & many are having problems, most of the time its only one bank that glows hot. What is really nice for the wallet is that sometimes one fails upon start up & bucks the engine backwards & messes up the timing & even bends some valves!

    My question would be to you is how long has this glowing hot been going on? Have you had the timing belts done recently & are the actual cam events happening at their correct times, do that camshaft marks line up with TDC. If the answer is yes, then it is a electronic timing issue & can only be fixed by replacing the OEM ignition units or try to get them repaired or using my direct coil set up that I have been selling for years.

    The advantage with my set up is that the timing is adjustable while the OEM system is not, there are no more dist caps or ignition rotors to replace & no more expensive ignition wires to buy. The timing is done from the front of the crankshaft with a 60 minus 2 tooth trigger wheel & a magnetic sensor, very accurate, to 1/4 of a degree at 20,000 RPM!
     
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  24. ME308

    ME308 Formula 3

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    #21 ME308, Oct 9, 2009
    Last edited by a moderator: Sep 7, 2017
    your headers shouldn`t glow...
    it`s not normal, no matter what people tell you

    most probably a timing problem -
    either mechanic (cams out of time) and/or electronic (marelli boxes) related

    first check your cam marks at tdc as Nick said...
    (when I first got my car, the 5-8 exhaust cam was 1 tooth out of time)

    and - to make things worse - one of my digiplexes hardly worked
    so even after correcting the cam position, result was still:
    red hot glowing headers all the time



    and that`s what it did for my car...

    no more glowing headers, 15K miles without the slightest bit of ignition trouble,
    running flawlessly and pulling stronger every day...

    changing to Nick`s XDI direct coil ignition, was certainly - together with birdman`s fusebox :) - the single best modification I did to my car



    best from Munich, Germany
    Michael
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  25. climb

    climb F1 Rookie

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    Correct me if wrong but i believe Jbryant's 308 has the electronic ignition and he still has header glow.
     

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