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red hot exhaust manifold - lt40 2.4 petrol/lpg

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nooberdoober View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nooberdoober Quote  Post ReplyReply Direct Link To This Post Topic: red hot exhaust manifold - lt40 2.4 petrol/lpg
    Posted: 16 Mar 13 at 01:40
Hi Everyone

I have been having probs with my old dog of a wagon again and I'm a bit lost.

I have been suffering power loss probs recently on both petrol and gas. I took it for a run tonight and spotted that the exhaust manifold was glowing red!!! Im pretty sure i've not seen this before, so wondered what could have changed.

I've heard that it can mean that perhaps I am running lean but not sure how this occurs. 
Also, I've heard it could be blocked cat.

I noticed that it glows less at lower speeds (if indeed its possible to go any slower), so less redhot at tickover than at full whack (47/50mph) :(

I had issues with the front end gas solenoid last week coming loose somehow. Very luckily I spotted the little nut, having fallen down on to the engine beneath. This was obviously stopping me getting ample gas through to the engine, and so once I'd fixed it, I presumed it would fix the power loss issue whilst on gas.
It improved briefly for about 30 miles, then back to it's gutless self.

Getting compression check done tmrw to see if ive got piston probs. will post results.

Any pointers would be welcome.

doober
I got me a 2.4 straight Six......and it's a soundin JUICY!

1984 LT40 2.4 petrol Coachbuilt Autotrail Motorhome
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mcbkat Quote  Post ReplyReply Direct Link To This Post Posted: 16 Mar 13 at 07:25
Would check the solenoid again, sounds like a lean mixture. But because it also occurs on petrol, check for airleaks in the inlet and check ignition-timing.

Stefan


Edited by mcbkat - 16 Mar 13 at 07:31
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nooberdoober Quote  Post ReplyReply Direct Link To This Post Posted: 16 Mar 13 at 11:31
Cheers Stefan,

funny enough, I have noticed some oil fouling around what looks to be the base of the carb. Could the dodgy old gasket have gone and be letting air in that way???? 

doob
I got me a 2.4 straight Six......and it's a soundin JUICY!

1984 LT40 2.4 petrol Coachbuilt Autotrail Motorhome
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Post Options Post Options   Thanks (0) Thanks(0)   Quote max and caddy Quote  Post ReplyReply Direct Link To This Post Posted: 16 Mar 13 at 11:40
Retarded timing can make the manifold glow...just tweak it and drive it...make a mark before moving the dizzy tho so you can revert..
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mcbkat Quote  Post ReplyReply Direct Link To This Post Posted: 16 Mar 13 at 13:11
Originally posted by nooberdoober nooberdoober wrote:

Could the dodgy old gasket have gone and be letting air in that way???? 


Since it's on both gas and petrol, that could very well be the cause.

Careful, lean mixture can make engine-parts melt...

Stefan
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nooberdoober Quote  Post ReplyReply Direct Link To This Post Posted: 16 Mar 13 at 13:36
Tnx once again folks. Your advice is invaluable.  Doob.
I got me a 2.4 straight Six......and it's a soundin JUICY!

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Post Options Post Options   Thanks (0) Thanks(0)   Quote nooberdoober Quote  Post ReplyReply Direct Link To This Post Posted: 28 Mar 13 at 11:55
Hi folks

Any Ideas where it would be possible to obtain gasket sets for old pierburg carbs? or alternative solution for carb on lt40 2.4 petrol. I think I remember someone saying they had put a webber on theirs....

Tnks in advance!

Doober
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nooberdoober Quote  Post ReplyReply Direct Link To This Post Posted: 28 Mar 13 at 13:07
Please ignore previous post as I have taken the age old advice of : VW Heritage. ;)

I should have looked before asking the question.

Doob
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nooberdoober Quote  Post ReplyReply Direct Link To This Post Posted: 28 Mar 13 at 22:47
Right then......Can't be bothered waiting a month for two bits of paper to come from Germany, so I have endeavoured to create my own. 

Bought some gasket paper today from a local motor factors for £1.50 (have ordered real ones as back up plan but cost me 35quids and will take a month to arrive) and today, set about creating nice new gaskets for the manifold>carb and for the float chamber.

Here's the top of the carb, with the face lightly sanded with some 600grit to clean it up. 



Here's the bottom bit, having had same treatment. (need to blow all the muck out before rebuilding)



The old duff manifold > carb gasket:



The really nasty old float chamber gasket:




The Manifold > Carb gasket was really easy, as I had enough of the old one to trace it directly onto paper and it's a very simple seal.

The float chamber Gasket was a total arse ache. The old one was kaput, as I had already reused it once, adding in some liquid gasket on the bad bits for good measure. This time, it all came apart when I removed it, so I painstakingly put it back together and laid it down flat under some clear tape. Scanned it in at 300dpi, traced in using by old buddy P.shop, adding symmetry and detail where there was only bent lines and mushed up old gasket. Next, I printed the new one out, went over it with dark soft pencil.



laid the drawing, graphite faced down onto the new gasket paper and scrubbed the image onto it.
Once the impression was transfered to the gasket paper, I spent the next three hours carefully hacking nearly perfect circles out of it with a scalpel. See below, they fit snug:



Hopefully tmrw, once I get a can of carb cleaner on it, get rid of any stray particles, I will try these out.

If anyone would like a copy of the scan, so they can save themselves the wait and the cost of importing new ones, I can email ya the jpeg for vw part number: 049 129 281 C


Doob.
I got me a 2.4 straight Six......and it's a soundin JUICY!

1984 LT40 2.4 petrol Coachbuilt Autotrail Motorhome
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jason k Quote  Post ReplyReply Direct Link To This Post Posted: 28 Mar 13 at 22:51
Nice work chap!! Let's hope this cures the problem
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nooberdoober Quote  Post ReplyReply Direct Link To This Post Posted: 28 Mar 13 at 23:13
Tnx Jason! I truly hope so.....otherwise im lost as to what it could be.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LTCamper89 Quote  Post ReplyReply Direct Link To This Post Posted: 28 Mar 13 at 23:44
Had plenty of those '?Can I have one like this?' in my recent past. I always used CAD to ready a file for CNC.

Well done Noober, another triumph over adversity. 

As JasonK says, hopefully that sorts it.Thumbs Up
1989 LT28 2.4D    Saviour of 6Music, well one of them. Now playing http://www.bbc.co.uk/radio/player/bbc_6music

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Post Options Post Options   Thanks (0) Thanks(0)   Quote nooberdoober Quote  Post ReplyReply Direct Link To This Post Posted: 30 Mar 13 at 15:03
Noooooooooooooooooooooooooooooooooooo!!!!!!!!!!

It was going sooo well.  :(




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Post Options Post Options   Thanks (0) Thanks(0)   Quote nooberdoober Quote  Post ReplyReply Direct Link To This Post Posted: 30 Mar 13 at 18:32
UPDATE: couple a hours later and my epoxy has set and the above cock-up sorted. Air intake collar back in place and all the new gaskets fitted. took it for a drive. Bugger all difference in power.......45mph tops. will take it out tonight to see if manifold still glows. if it doesn't glow, I guess the new gaskets did their job. But where did my precious 5mph go off my top end????????? I know it sounds daft but 5mph makes a massive difference in this thing. I can take it on the motorway at 50-50mph but not at 45.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nooberdoober Quote  Post ReplyReply Direct Link To This Post Posted: 30 Mar 13 at 19:43
UPDATE 2: exhaust branch still glowing red. Out of Ideas, sick to death. 

I did spot a little trickle of water coming from somewhere between the intake manifold and the exhaust manifold. Could this be the damn head gasket? or poor seal on the intake manifold?

Sorry for all this posting. I am most definitely turning desperado.

The Grand Novisimmo. AKA. Doober.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AndyT Quote  Post ReplyReply Direct Link To This Post Posted: 31 Mar 13 at 14:18
Running so hot could well have caused damage.
Suggest a compression test and an emmisions check.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nooberdoober Quote  Post ReplyReply Direct Link To This Post Posted: 01 Apr 13 at 11:00
TOP END SPEED ISSUE FIXED!!!!! Throttle cable was totally inefficient (which I kinda knew) and was fixed yesterday by a rather clever chappy. We cut and welded the bracket that holds the accelerator cable into a a better position to allow the cable to operate the throttle to through its full range.

Customised bracket:



Customised throttle:



Also he spotted that..............the 2nd stage vacuum was knackered, so for the entire life of my vehicle I've never had the second venturi opening. He fixed it by making the action that was usually controlled by the vacuum, sprung loaded. Now, I can literally drive at 60mph in 5th gear and it keeps pulling. 

HOT EXHAUST ISSUE NOT FIXED: The Exhaust branch still gets hot at full speed though so need to continue to find the reason for that. He seemed to think that as I had 6 infernos jumping out of the exhaust ports, that it was natural for them to get hot. I can see that logic. 

TNx for everyones input.

----------------------------------




Edited by nooberdoober - 15 Jul 17 at 09:32
I got me a 2.4 straight Six......and it's a soundin JUICY!

1984 LT40 2.4 petrol Coachbuilt Autotrail Motorhome
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nooberdoober Quote  Post ReplyReply Direct Link To This Post Posted: 01 Apr 13 at 12:30
Originally posted by AndyT AndyT wrote:

Running so hot could well have caused damage.
Suggest a compression test and an emmisions check.

Hi Andy

Compression was good apparently. I got that checked the other day. lowest was 135psi highest was 150.
I would like to get the emissions checked though. Is there any way novice can get an idea of emissions without sophisticated kit?

Doob
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AndyT Quote  Post ReplyReply Direct Link To This Post Posted: 01 Apr 13 at 16:03
No, a basic gas tester like mine costs around £100.
Best bet is your local garage, or as I always recommend a mobile tuner who can adjust timing, mixture etc to suit the vehicle.
Cost is only £40ish, a lot less than a new engine and when something is wrong pays for itself in no time.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nooberdoober Quote  Post ReplyReply Direct Link To This Post Posted: 15 Jul 17 at 09:32
UPDATE - 2017:  Wagon not been driven for a long time and been stored. MOT'd and given lots of love ready for the road again, I looked back into the old issue or red hot exhaust pipe while at speed....

MOT failed because of excess HydroCarbon (running on LPG) unburnt in exhaust gases. 

So we looked at the timing with a strobe and noticed that it needed tweaking at tickover to get the timing marks to line up. It was a degree or three behind the mark. I tweaked the distributor so that the marks line up. With this done, we looked how it advanced under load because it is only at high speed that the exhaust glows (sustained 50mph plus).

When I took the motor for a test on the way home that night, i checked the exhaust again after some sustained 50mph it was surely red hot again. Not good, I thought. 

So next is to tweak the timing while i drive it and see if there is a better setting and to watch for more or less cherry red exhaust....

---- QUESTION ---- Does anyone know from experience how much the timing marks should advance past the btdc marking? Should it ever advance so much that you can't see it anymore in the bellhousing cutout? Or should is always be visible just further forward?

Doob.



Edited by nooberdoober - 15 Jul 17 at 14:35
I got me a 2.4 straight Six......and it's a soundin JUICY!

1984 LT40 2.4 petrol Coachbuilt Autotrail Motorhome
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