glowing manifolds - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jamal · 08-13-2005, 11:31 PM

I know this is not the right forum but I've posted elsewhere with no response. You guys know your stuff and am sure you can help that is why I ask. I finally have my 98 running again. I broke the new engine in tonight. The only thing that I thought was strange was while I was breaking the engine in the manifolds started glowing. It was dark out and when I shined a flashlight on them they didnt look red anymore. Was it b/c it was dark and was running engine between 2500 and 3000rpm without any moving air? I couldn't find any vacuum leaks and everything was sealed from mass air back to the intake. Ran good and oil pressure was around 80 at start up and droped to around 45 when warm and temp stayed in normal range. Anything to worry about or is it normal? I never broke an engine in at night so I have no idea if it is normal or not.

LooseCannon · 08-14-2005, 12:34 AM

My friend's 78 blazer did the same thing. It was caused by running to lean.

Cat Fuzz · 08-14-2005, 12:42 AM

Running too lean, plugged cat or other exhaust restriction.

jamal · 08-14-2005, 12:54 AM

but my fuel is controlled by computer. Think my timing might be off? didn't get any engine light. will look again for vacuum leaks in the am

jimfulco · 08-14-2005, 01:18 AM

Retarded timing?

chevman-67 · 08-14-2005, 11:44 AM

Check the cataletic converters they are probably plugged or muffler is plugged.or your doughnuts in the exhaust are blocking part of yourmanifold to y-pipe .sounds like I would start there first.

*Randy70C-10* · 08-14-2005, 12:09 PM

Either running too lean or you have a BIG vacuum leak. Everything that I've seen from plugged cats usually makes everything "behind" them glow.

jamal · 08-14-2005, 09:44 PM

was my timing it was advanced too much

mocwon · 08-14-2005, 10:23 PM

Agree w/Randy. Seen cats back glow when cats are plugged but not forward.

roger0080 · 08-14-2005, 10:59 PM

I was driving a UPS truck that had an old Ford 6 cylinder in it at about 55 mph down the freeway when the engine cover in the cab blew backwards exposing the engine and much to my surprise the exhaust manifold was all orange! Never thought much about what color if any the manifold changes while we are driving. I wouldn't worry about it. Hope this helps.

al's71gmc · 08-14-2005, 11:26 PM

sounds like you already got it, but i had glowing manifolds on a toyota, and it was the timing.

ZOOMY · 08-14-2005, 11:45 PM

Most engines will get the manifolds glowing at night if you run them long enough at 3k. It happens quicker with headers. Exhaust ges temperature is about 1500 degrees at ideal mixture. It drops off if it's runnung lean or rich from that point.

jamal · 08-15-2005, 10:35 PM

thought I had it fixed they are still glowing. I drove it at night pretty hard and they turned bright red. I cant find vacuum leak or anything and timing is dead on. this is a brand new longblock and hate to mess it up as I dont have money to buy another one. Engine is not getting hot or anything, just manifolds. Should I worry? This truck has a 3 inch body lift so it allows me to see manifolds, and may just not have noticed in other vehicles. I bought it with a spun main so I have no idea if it did it before. I am confused as hell please help could I have valves too tight?

gator2511 · 08-15-2005, 11:22 PM

You are too lean. If you are using an electric fuel pump check your fuel pressure. Had a buddy's electric fuel pump that went bad but it didn't just die. It reduced the fuel volume and pressure to the engine, the engine ran lean, manifolds glowed orange. Your computer may be happy with fuel information as far as it knows but it doesn't know the pump can't deliver enough gas. Its worth a try. Two months later mine went but it died suddenly.

lowrider79 · 08-15-2005, 11:45 PM

Try changing the fuel filter as well

**Richard** · 08-16-2005, 02:12 AM

I saw that happen years ago on a friends engine. The cam flattened out during break-in. I hope everything is okay.

jamal · 08-16-2005, 05:54 PM

pulled plugs and they look great, no signs of running lean or rich. It is running right and the timing is dead on with a scan tool. Has to be ok if plugs are looking good and timing is dead on right?

*Randy70C-10* · 08-16-2005, 06:05 PM

Try advancing the timing one or two degrees and try again. Timing advanced too much won't make them glow (normally) but having it retarded too much will. What happens is if the timing is retarded too much (meaning it's firing too late) then you have fire going out of your heads instead of burnt gases (exhaust). That's the best I can explain it (I'm a redneck)

You should see what timing does to a 6:71 blown 350 when it's retarded too much. The headers turn white!

jamal · 08-16-2005, 06:32 PM

actually when I thought I was adjusting timing I wasn't. the timing on vortecs is non adjustable, and I was only confusing computer. Could it be improper ex valve adjustment? Everything seems right though.

08-13-2005, 11:31 PM	#1
jamal Registered User Join Date: Apr 2005 Location: Bridgeport, AL Posts: 363	glowing manifolds, help still glow I know this is not the right forum but I've posted elsewhere with no response. You guys know your stuff and am sure you can help that is why I ask. I finally have my 98 running again. I broke the new engine in tonight. The only thing that I thought was strange was while I was breaking the engine in the manifolds started glowing. It was dark out and when I shined a flashlight on them they didnt look red anymore. Was it b/c it was dark and was running engine between 2500 and 3000rpm without any moving air? I couldn't find any vacuum leaks and everything was sealed from mass air back to the intake. Ran good and oil pressure was around 80 at start up and droped to around 45 when warm and temp stayed in normal range. Anything to worry about or is it normal? I never broke an engine in at night so I have no idea if it is normal or not. __________________ 67 chevy stepside, 6 cylinder, three on the tree, small window. Currently in resto. Last edited by jamal; 08-15-2005 at 10:41 PM.

08-14-2005, 12:42 AM	#3
Cat Fuzz My son, my joy. Join Date: Sep 2003 Location: Spokane WA Posts: 463	Running too lean, plugged cat or other exhaust restriction. __________________ '69 Chevy 3/4 ton, 327cid, Carter AFB, Edelbrock intake, HEI, TH400. Founding member of the No Money To Spend On My Truck Club. When your at Home Depot, you WISH you had gotten an 8 foot bed!

08-14-2005, 12:54 AM	#4
jamal Registered User Join Date: Apr 2005 Location: Bridgeport, AL Posts: 363	but my fuel is controlled by computer. Think my timing might be off? didn't get any engine light. will look again for vacuum leaks in the am __________________ 67 chevy stepside, 6 cylinder, three on the tree, small window. Currently in resto.

08-14-2005, 11:44 AM	#6
chevman-67 Registered User Join Date: Jul 2004 Location: quebec canada Posts: 135	Check the cataletic converters they are probably plugged or muffler is plugged.or your doughnuts in the exhaust are blocking part of yourmanifold to y-pipe .sounds like I would start there first. __________________ gm's are #1 1967 chevrolet short step 1988 chev 4x4 1/2 ton 1989 gmc 1/2 ton 1991 chev 1/2 ton 4x4 1993 Jeep grand cherokee 4x4 And yes a 94 Ford Mustang.

08-14-2005, 09:44 PM	#8
jamal Registered User Join Date: Apr 2005 Location: Bridgeport, AL Posts: 363	was my timing it was advanced too much __________________ 67 chevy stepside, 6 cylinder, three on the tree, small window. Currently in resto.

08-14-2005, 12:34 AM	#2
LooseCannon Registered User Join Date: Mar 2004 Location: Boiling Springs, PA Posts: 391	My friend's 78 blazer did the same thing. It was caused by running to lean.

08-14-2005, 01:18 AM	#5
jimfulco Registered User Join Date: May 2003 Location: Shreveport LA Posts: 3,170	Retarded timing?

08-14-2005, 12:09 PM	#7
Randy70C-10 Account Suspended Join Date: Mar 2001 Location: Virginia Beach, Va. U.S.A. Posts: 15,320	Either running too lean or you have a BIG vacuum leak. Everything that I've seen from plugged cats usually makes everything "behind" them glow.

08-14-2005, 10:23 PM	#9
mocwon Keep On Truckin' Join Date: Mar 2003 Location: Buda, Texas Posts: 1,354	Agree w/Randy. Seen cats back glow when cats are plugged but not forward. __________________ Just Passin' Thru Some projects are like herding cats; others are like putting out fires; this one was like herding cats on fire.....

08-14-2005, 10:59 PM	#10
roger0080 Registered User Join Date: Nov 2000 Location: Carver County, Minnesota, USA Posts: 626	I was driving a UPS truck that had an old Ford 6 cylinder in it at about 55 mph down the freeway when the engine cover in the cab blew backwards exposing the engine and much to my surprise the exhaust manifold was all orange! Never thought much about what color if any the manifold changes while we are driving. I wouldn't worry about it. Hope this helps. __________________ 72 Chev C-10 90% restored (former AZ truck) ... 71 Chev K-20 Cheyenne my vacation crusier... 72 Chev C-10 Now retired and striped after many faithful miles... 72 GMC 1500 Retired to the junk yard after bought new in '71...

08-14-2005, 11:26 PM	#11
al's71gmc 4 eyed fever Join Date: Jul 2005 Location: Eureka, Nevada Posts: 500	sounds like you already got it, but i had glowing manifolds on a toyota, and it was the timing. __________________ 1971 GMC 2500 4x4 1972 GMC Sierra Grande 1/2 t 4x4-#1 son's truck. Recently completed resto. 4 YO daughter," Daddy, I like your truck better than Mom's." (2000 F350-ranch truck) Smart kid!!

08-14-2005, 11:45 PM	#12
ZOOMY Senior Member Join Date: Feb 2003 Location: WIS Posts: 1,752	glowing Most engines will get the manifolds glowing at night if you run them long enough at 3k. It happens quicker with headers. Exhaust ges temperature is about 1500 degrees at ideal mixture. It drops off if it's runnung lean or rich from that point.

08-15-2005, 10:35 PM	#13
jamal Registered User Join Date: Apr 2005 Location: Bridgeport, AL Posts: 363	thought I had it fixed they are still glowing. I drove it at night pretty hard and they turned bright red. I cant find vacuum leak or anything and timing is dead on. this is a brand new longblock and hate to mess it up as I dont have money to buy another one. Engine is not getting hot or anything, just manifolds. Should I worry? This truck has a 3 inch body lift so it allows me to see manifolds, and may just not have noticed in other vehicles. I bought it with a spun main so I have no idea if it did it before. I am confused as hell please help could I have valves too tight? __________________ 67 chevy stepside, 6 cylinder, three on the tree, small window. Currently in resto. Last edited by jamal; 08-15-2005 at 10:36 PM.

08-15-2005, 11:22 PM	#14
gator2511 Registered User Join Date: Mar 2005 Location: tampa florida Posts: 776	You are too lean. If you are using an electric fuel pump check your fuel pressure. Had a buddy's electric fuel pump that went bad but it didn't just die. It reduced the fuel volume and pressure to the engine, the engine ran lean, manifolds glowed orange. Your computer may be happy with fuel information as far as it knows but it doesn't know the pump can't deliver enough gas. Its worth a try. Two months later mine went but it died suddenly. Last edited by gator2511; 08-15-2005 at 11:26 PM.

08-15-2005, 11:45 PM	#15
lowrider79 Registered User Join Date: Jul 2004 Location: Shakopee Minnesota Posts: 174	Try changing the fuel filter as well



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08-16-2005, 02:12 AM	#16
Richard Senior Member Join Date: Dec 1999 Location: Southern California Posts: 2,897	I saw that happen years ago on a friends engine. The cam flattened out during break-in. I hope everything is okay. __________________ Richard 1972 K10 Custom Deluxe SWB Fleetside My build https://67-72chevytrucks.com/vboard/...d.php?t=800746

08-16-2005, 05:54 PM	#17
jamal Registered User Join Date: Apr 2005 Location: Bridgeport, AL Posts: 363	pulled plugs and they look great, no signs of running lean or rich. It is running right and the timing is dead on with a scan tool. Has to be ok if plugs are looking good and timing is dead on right? __________________ 67 chevy stepside, 6 cylinder, three on the tree, small window. Currently in resto.

08-16-2005, 06:05 PM	#18
Randy70C-10 Account Suspended Join Date: Mar 2001 Location: Virginia Beach, Va. U.S.A. Posts: 15,320	Try advancing the timing one or two degrees and try again. Timing advanced too much won't make them glow (normally) but having it retarded too much will. What happens is if the timing is retarded too much (meaning it's firing too late) then you have fire going out of your heads instead of burnt gases (exhaust). That's the best I can explain it (I'm a redneck) You should see what timing does to a 6:71 blown 350 when it's retarded too much. The headers turn white! Last edited by Randy70C-10; 08-16-2005 at 06:06 PM.

08-16-2005, 06:32 PM	#19
jamal Registered User Join Date: Apr 2005 Location: Bridgeport, AL Posts: 363	actually when I thought I was adjusting timing I wasn't. the timing on vortecs is non adjustable, and I was only confusing computer. Could it be improper ex valve adjustment? Everything seems right though. __________________ 67 chevy stepside, 6 cylinder, three on the tree, small window. Currently in resto. Last edited by jamal; 08-16-2005 at 06:34 PM.

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