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Type 4 exhaust manifold glowing red following rebuild
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Paddyvan
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PostPosted: Tue Sep 13, 2016 8:53 am    Post subject: Type 4 exhaust manifold glowing red following rebuild Reply with quote

Hi,
I am new to this site and to the world of aircooled engines.
As part of a full restoration of a '79 Westfalia the engine was machined and rebuilt due to excessive crankshaft endplay. It is a GE code engine with hydraulic lifters.
To make a long story short when the engine was started the exhaust manifold on the LHS started to glow orange/red after a couple of minutes at idle. The manifold on the RHS is not visible because it is covered by the heat exchanger. To establish if it was a problem with all four exhaust ports I removed the two manifolds and ran the engine again. Flames were coming out of all four ports an each exhaust stroke.
Any words of wisdom on diagnosing this problem would be gratefully appreciated as I don't want to toast it this early after the rebuild.
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sjbartnik
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PostPosted: Tue Sep 13, 2016 9:12 am    Post subject: Re: Type 4 exhaust manifold glowing red following rebuild Reply with quote

Is this Bus a USA import? Is it fuel injected or does it have carbs?

Is there a catalytic converter? If so, is it clogged?

Clearly a glowing red exhaust manifold at idle is not normal.
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WhirledTraveller
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PostPosted: Tue Sep 13, 2016 10:10 am    Post subject: Re: Type 4 exhaust manifold glowing red following rebuild Reply with quote

likely a camshaft timing issue. Exhaust valves opening too early allowing combustion to occur inside the exhaust. Not good. Pray that I'm wrong, because if I'm right the case has to be split again.

Other things that could cause this are incomplete exhaust valve closing, severely retarded ignition timing, or consistent misfiring. Basically anything that lets unburnt fuel into the exhaust.
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Last edited by WhirledTraveller on Tue Sep 13, 2016 10:17 am; edited 1 time in total
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kooper271
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PostPosted: Tue Sep 13, 2016 10:17 am    Post subject: Re: Type 4 exhaust manifold glowing red following rebuild Reply with quote

WhirledTraveller wrote:
likely a camshaft timing issue. Exhaust valves opening too early allowing combustion to occur inside the exhaust. Not good. Pray that I'm wrong, because if I'm right the case has to be split again.


How would one mess up the crankshaft timing like this? The crankshaft and camshaft have timing marks, no?
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WhirledTraveller
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PostPosted: Tue Sep 13, 2016 10:20 am    Post subject: Re: Type 4 exhaust manifold glowing red following rebuild Reply with quote

kooper271 wrote:
WhirledTraveller wrote:
likely a camshaft timing issue. Exhaust valves opening too early allowing combustion to occur inside the exhaust. Not good. Pray that I'm wrong, because if I'm right the case has to be split again.


How would one mess up the crankshaft timing like this? The crankshaft and camshaft have timing marks, no?


Well it's possible to mess it up if you're not careful. But maybe I was too doom and gloom. Could be other things. I edited my post. Start with the ignition timing, easiest to check and easiest to get wrong. Late spark will mean the mixture will still be burning at the start of the exhaust stroke.
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SGKent Premium Member
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PostPosted: Tue Sep 13, 2016 10:54 am    Post subject: Re: Type 4 exhaust manifold glowing red following rebuild Reply with quote

Is this red glow at RPM under load, with the engine RPM raised up, or just at idle? What tin is in place? Are the sleds there? Air coming from the engine should be passing over the cylinders and heads, then headed to the exhaust stacks.

That said, anything that causes the burn to extend into the exhaust stacks would cause them to get very hot. As Whirled Traveler and others have said, that could be an overly lean mixture, too retarded timing, old gasoline that burns really slow etc. HOWEVER if on the other hand the engine was on a dyno under heavy load, and held at near full load I would expect the header to show some color - maybe red or straw.

Richard Atwell took some measurements on a normally running bus and saw 700F at the F-pipes. Steel begins to glow around 900F so it is critical that the air flow, mixture and timing to all be correct.

http://www.ratwell.com/technical/Temps.html
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kooper271
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PostPosted: Tue Sep 13, 2016 2:08 pm    Post subject: Re: Type 4 exhaust manifold glowing red following rebuild Reply with quote

WhirledTraveller wrote:
kooper271 wrote:
WhirledTraveller wrote:
likely a camshaft timing issue. Exhaust valves opening too early allowing combustion to occur inside the exhaust. Not good. Pray that I'm wrong, because if I'm right the case has to be split again.


How would one mess up the crankshaft timing like this? The crankshaft and camshaft have timing marks, no?


Well it's possible to mess it up if you're not careful. But maybe I was too doom and gloom. Could be other things. I edited my post. Start with the ignition timing, easiest to check and easiest to get wrong. Late spark will mean the mixture will still be burning at the start of the exhaust stroke.



I wasn't trying to correct you, I was genuinely curious. Thanks for clarifying.
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orwell84
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PostPosted: Tue Sep 13, 2016 5:12 pm    Post subject: Re: Type 4 exhaust manifold glowing red following rebuild Reply with quote

Were you raising the idle speed to break in a new cam? New P and C's? A rebuilt engine will get quite hot when running in and I have seen many posts on forums about glowing exhaust headers when running in a new engine, even water cooled. I would expect to see flame coming out of exhaust ports on an engine with no headers.
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Wildthings
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PostPosted: Tue Sep 13, 2016 8:08 pm    Post subject: Re: Type 4 exhaust manifold glowing red following rebuild Reply with quote

I would suspect the valves to start with. Are you running hydraulic lifters still? If so then once preloaded one or more lifters may take a while to self adjust and not seal well until it(they) do. If you have solids then check your adjustment one more time.

Set your engine timing statically to 7-8° BTDC or running at 28° BTDC @3500rpm with the hose(s) off and plugged. If you have not run this engine previously and know for sure the timing mark on the pulley is correct then go to Ratwell.com and follow the procedure for verifying the timing mark. You much have a timing scale to time one of these engines correctly, if you try to time it to the case split you are going to have the timing very far retarded.
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Paddyvan
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PostPosted: Wed Sep 14, 2016 6:51 am    Post subject: Re: Type 4 exhaust manifold glowing red following rebuild Reply with quote

Many thanks for all the replies.
To answer some of the questions asked:
- It is a US import with a single carb.
- It does not have a catalytic converter.
- I had thought about camshaft timing but I am happy that it is correct.
- The red header is at idle. I did not continue running it.
- Gasoline is new.
- The engine has no tin fitted as it is being run in a stand.
- Engine has hydraulic lifters. They all feel stiff before start up.

I will have a look at timing and mixture again over the weekend and report back. Thanks again.
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PostPosted: Wed Sep 14, 2016 6:54 am    Post subject: Re: Type 4 exhaust manifold glowing red following rebuild Reply with quote

with no tin it has no cooling.
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PostPosted: Wed Sep 14, 2016 7:41 am    Post subject: Re: Type 4 exhaust manifold glowing red following rebuild Reply with quote

Don't run it without tin, even on the stand. You need the over-cylinder tin, the fan housing, the flaps inside the fan housing, and the fan to be installed at the very least before running the engine on the stand.
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Paddyvan
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PostPosted: Wed Sep 14, 2016 8:16 am    Post subject: Re: Type 4 exhaust manifold glowing red following rebuild Reply with quote

Info re. tin is noted. Will fit it before running again. Thanks.
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Wildthings
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PostPosted: Wed Sep 14, 2016 8:25 am    Post subject: Re: Type 4 exhaust manifold glowing red following rebuild Reply with quote

Paddyvan wrote:

- Engine has hydraulic lifters. They all feel stiff before start up.


If your lifters were hard before you set the preload then one or more of them may need time to self adjust. Until then you will have a valve or three that are not closing fully. It is sometimes even hard to get an engine with hydraulic lifters to start the first time after the valves have been preloaded as the engine will lack compression across the board. Given two to five minutes of running your problem may well go away on its own.

Also if the lifters were not pumped up fully and you failed to notice the point of zero lash, which can be very subtle, you may actually have set the preload way passed the ability of the lifters to self adjust.

In either case you might want to back the adjusters off and reset them with ~ .006" of lash and then run the engine for a bit to get the lifters to pump up fully and then go back and reset them. When preloading the lifters just use your fingers to turn the screws in being very careful to feel for the first contact, if you do this step with a screwdriver it is all to easy to miss.

As others have said, do not run an engine without the tin and the rest of the cooling system in place. You could do serious damage in just a few minutes even at a low idle.
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PostPosted: Wed Sep 14, 2016 8:48 am    Post subject: Re: Type 4 exhaust manifold glowing red following rebuild Reply with quote

Paddyvan wrote:
Info re. tin is noted. Will fit it before running again. Thanks.


Keep these numbers in mind - Steel begins to turn red at 1000 degrees F. It is cherry red at 1200F - 1300F. Aluminum melts around 1220F.
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Schwing
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PostPosted: Fri Mar 24, 2017 9:17 pm    Post subject: Re: Type 4 exhaust manifold glowing red following rebuild Reply with quote

Did you ever experience this again or figure out what it was? My freshly built 1.7 with stainless steel headers is doing this on the cylinder 1&2 side. I'm hoping this is just a timing issue or a carb adjustment.
I haven't driven it yet under load, this is at idle within 2-3min of starting it up. The chokes have it at a very high idle 2k+. Another odd symptom is that the idle speed increases from 1000 to 2000 when the air cleaner horns go on the carbs. Odd stuff.
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PostPosted: Fri Mar 24, 2017 10:06 pm    Post subject: Re: Type 4 exhaust manifold glowing red following rebuild Reply with quote

What Ian your ignition timing set to? I can cook food on my apron by retarding the timing and letting the engine idle.

I don't want to speculate too wildly... but what carbs do you have? If you make a change to the mixture in any one direction, and the engine raises in speed, then the engine liked your change. So if restricting the air improves the increases the idle speed, then the engine might be running lean, which would add to a heat issue.

Robbie
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bbrowncods
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PostPosted: Sat Apr 29, 2017 2:01 pm    Post subject: Re: Type 4 exhaust manifold glowing red following rebuild Reply with quote

Old gas...
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PostPosted: Sat Apr 29, 2017 2:45 pm    Post subject: Re: Type 4 exhaust manifold glowing red following rebuild Reply with quote

bbrowncods wrote:
Old gas...


Sounds like you need to cut back on the gas station bean burritos.
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