GMCforum
For enthusiast of the Classic GMC Motorhome built from 1973 to 1978. A web-based mirror of the GMCnet mailing list.
Home » Public Forums » GMCnet » OEM intake manifolds and cracks, symptoms?
Re: [GMCnet] OEM intake manifolds and cracks, symptoms? [message #335507 is a reply to message #335503] Mon, 23 July 2018 11:11 Go to previous messageGo to previous message
James Hupy is currently offline  James Hupy   United States
Messages: 6806
Registered: May 2010
Karma:
Senior Member
Cracked intake manifolds exhibit the exact symptoms you describe, as well
as higher than normal oil consumption. They run just fine when cold, but,
as the engine warms up, it runs worse and worse depending upon the severity
of the crack. If the floor of the inlet tract is cracked, it can easily be
seen by removing the carb and shining a powerful light source down the
intake.
If it is only cracked between the crossover and the engine valley, the
runability is not affected as much, but oil consumption will still be
prevalent.
Jim Hupy
Salem, Or

On Mon, Jul 23, 2018, 8:33 AM slc wrote:

> GMC2000 wrote on Mon, 23 July 2018 00:34
>> reading about the intake problems where the exhaust crossover heat
> becomes excessive, possibly when one side of the exhaust system has a leak.
> it
>> seems to be a very common problem (both the exhaust manifold leaks and
> cracked intakes)
>>
>> but what are the symptoms of a cracked intake as it develops and
> progresses? I read Jim Bounds blog post about how the engine runs fine
> until it
>> gets up to operating temp then it wont take any throttle and just dies
> when you try to go above idle but is there any indications in drive-ability
>> that it may be cracking before the crack gets this big?
>
>
>
> I had a fuel system problem when we found by accident, the cracks in the
> exhaust crossover. So under this scenario, there were no symptoms. Also,
> the cracks could not be seen. We removed the manifold for a different
> reason and the cracks didn't show up until we attempted to clean it. I had
> cracks on both the top and bottom of the manifold and the crack lines did
> not show up until the cleaner was applied and wetted the metal. Even then,
> these long cracks were difficult to see
> When the fuel tanks were bypassed and I was using an aux tank, no
> symptoms and the engine would run fine. After looking at the cracks it was
> determined that the cracks were not new at all, and had been there for a
> long time.
> --
> GatsbysCruise. \
> 74GMC260 Former Glacier Model style. \
> Waukegan, Illinois \ Keep those MiniDiscs Spinning \ MY GREYHOUND IS
> FASTER THAN YOUR HONOR ROLL STUDENT \ WindowsXP-Win7-Win8.1-UBUNTU STUDIO -
> UBUNTU VOYAGER - Berzin Auto Center
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

Report message to a moderator

[Message index]
 
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Previous Topic: [GMCnet] FMCA Roadside rescue,problem
Next Topic: FMCA Roadside Rescue problem
Goto Forum:
  


Current Time: Sun May 19 09:41:41 CDT 2024

Total time taken to generate the page: 0.00611 seconds
.:: Contact :: Home ::.

Powered by: FUDforum 3.1.1.
Copyright ©2001-2021 FUDforum Bulletin Board Software