Intake crossover repair

J

jerry burt

New member
Feb 13, 2016
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I'm going to pull my intake because of oil leaks front and rear. I've done a search on crossover repair in case my intake is cracked. It appears the
intake has been off before, bulging silicon for valley seals, so I don't know what I will find. Still trying to locate some history on the drive
train.

Back in 2015 Peer had a discussion with Dick Patterson about crossover block-offs and crack repair options. I didn't see any followup on Peer's tests.
I'm wondering if there were any results or if there are any new procedures.

--
Patti & Jerry Burt
73 Gmc 26' Canyon Lands -
Photos - http://jburt.smugmug.com/GMC-Motorhome
Lots of upgrades but lots to do to make it ours.
Members: FMCA - GMCMI - GMCWS - Pacific Cruisers - 49ers
 
Jerry,

If you block the crossover the temperature in that area will drop from 1100+
degrees Fahrenheit to that of the oil vapors in the area (around 170) or
that of the oil itself (around 250). I have a photo that Dick sent to me
showing a laser temp sensor "shooting" the temp through the choke stove port
to the bottom of the plenum and it is reading 173F.

The surface of the plenum under the carb would be even less as the gasoline
in the intake air vaporizes.

Regards,
Rob M.
The Pedantic Mechanic
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808

-----Original Message-----
From: Jerry Burt

I'm going to pull my intake because of oil leaks front and rear. I've done a
search on crossover repair in case my intake is cracked. It appears the
intake has been off before, bulging silicon for valley seals, so I don't
know what I will find. Still trying to locate some history on the drive
train.

Back in 2015 Peer had a discussion with Dick Patterson about crossover
block-offs and crack repair options. I didn't see any followup on Peer's
tests.
I'm wondering if there were any results or if there are any new procedures.

--
Patti & Jerry Burt
 
The contrast, or difference in temperatures, within the casting is what is
responsible for cracking. That and the loss of carbon and other elements
from the erosion of the casting due to application of exhaust gasses laden
with combustion byproducts starved for oxygen. EXCEPT IN COLD WEATHER,
there is no down side to blocking the crossover.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

> Jerry,
>
> If you block the crossover the temperature in that area will drop from
> 1100+
> degrees Fahrenheit to that of the oil vapors in the area (around 170) or
> that of the oil itself (around 250). I have a photo that Dick sent to me
> showing a laser temp sensor "shooting" the temp through the choke stove
> port
> to the bottom of the plenum and it is reading 173F.
>
> The surface of the plenum under the carb would be even less as the gasoline
> in the intake air vaporizes.
>
> Regards,
> Rob M.
> The Pedantic Mechanic
> USAussie - Downunder
> AUS '75 Avion - The Blue Streak TZE365V100428
> USA '75 Avion - Double Trouble TZE365V100426
> USA '77 Kingsley - TZE 267V100808
>
> -----Original Message-----
> From: Jerry Burt
>
> I'm going to pull my intake because of oil leaks front and rear. I've done
> a
> search on crossover repair in case my intake is cracked. It appears the
> intake has been off before, bulging silicon for valley seals, so I don't
> know what I will find. Still trying to locate some history on the drive
> train.
>
> Back in 2015 Peer had a discussion with Dick Patterson about crossover
> block-offs and crack repair options. I didn't see any followup on Peer's
> tests.
> I'm wondering if there were any results or if there are any new procedures.
>
> --
> Patti & Jerry Burt
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
I pulled my 1975 intake two weeks ago to put in the Paterson blockoff kit I bought over a year ago. Visible cracks on the bottom. Called Dick last
week and he said put it back together with the stainless block offs I already had, that the cracks shouldn't even open up after they don't get the
exhaust heat. Google Springfield Ignition for his contacts, he is one of the most helpful people ever.
--
1975 Glenbrook, 1978 Royale rear bath
Raleigh, NC
 
Thanks for the feedback everyone.
I have a second intake that is cracked in the secondary web and into the lifter valley. I had been wondering if I couldn't groove and fill the lower
crack with high temp Liquid Steel but was concerned about it possibly falling out. I think I'll leave them and see how that goes.

Rob, I'm sorry, I said it was Peer and it was your posts in this thread:
http://gmc.mybirdfeeder.net/GMCforum/index.php?t=msg&goto=274926&rid=5019&srch=intake+manifold+repair
I was wondering if you had followed up with those experiments.

Thanks again All.
--
Patti & Jerry Burt
73 Gmc 26' Canyon Lands -
Photos - http://jburt.smugmug.com/GMC-Motorhome
Lots of upgrades but lots to do to make it ours.
Members: FMCA - GMCMI - GMCWS - Pacific Cruisers - 49ers
 
Since manifold cracking is a common problem on our application, I have to wonder: Is it a problem with the lower profile manifolds? Is it common on
Toronados?

I dont remember hearing about it being a common olds V8 isssue across the board.
--
76 Glenbrook
 
> I'm going to pull my intake because of oil leaks front and rear. I've done a search on crossover repair in case my intake is cracked. It appears
> the intake has been off before, bulging silicon for valley seals, so I don't know what I will find. Still trying to locate some history on the drive
> train.
>
> Back in 2015 Peer had a discussion with Dick Patterson about crossover block-offs and crack repair options. I didn't see any followup on Peer's
> tests. I'm wondering if there were any results or if there are any new procedures.
No new procedures. While you got it off, block the crossover with the stainless steel plate kit and add an electric choke.

Jim K (AppliedGMC) has everything you need. 1-800-752-7502

--
73 23' Sequoia 4 Sale
73 23' CanyonLands Parts Unit 4 Sale
Upper Alabama
"When I grow up I am going to be a curmudgeon."
 
Do yourself a favor and stop reading the "hot rod Oldsmobile forum".
455 Oldsmobiles used in GMC"S have a huge load on them compared to a
4-4-2 or a Cutlass Supreme or a Toronado.
The exhaust gasses from a GMC are much greater in volume as well as
temperature, due to the 12,000 pound weight of the coach. The coolant and
oil temperatures are much hotter as well. These extremes are what Crack
manifolds.
Jim Hupy

> Since manifold cracking is a common problem on our application, I have to
> wonder: Is it a problem with the lower profile manifolds? Is it common on
> Toronados?
>
> I dont remember hearing about it being a common olds V8 isssue across the
> board.
> --
> 76 Glenbrook
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
> > I'm going to pull my intake because of oil leaks front and rear. I've done a search on crossover repair in case my intake is cracked. It
> > appears the intake has been off before, bulging silicon for valley seals, so I don't know what I will find. Still trying to locate some history on
> > the drive train.
> >
> > Back in 2015 Peer had a discussion with Dick Patterson about crossover block-offs and crack repair options. I didn't see any followup on
> > Peer's tests. I'm wondering if there were any results or if there are any new procedures.
> No new procedures. While you got it off, block the crossover with the stainless steel plate kit and add an electric choke.
>
> Jim K (AppliedGMC) has everything you need. 1-800-752-7502


Thanks for the update. The block-off gaskets, electric choke, and a Patterson distr. w/plugs and wires are going in. While I'm at it, a new thermostat
and Jim Ks insulated, flex gas line will go in also.

--
Patti & Jerry Burt
73 Gmc 26' Canyon Lands -
Photos - http://jburt.smugmug.com/GMC-Motorhome
Lots of upgrades but lots to do to make it ours.
Members: FMCA - GMCMI - GMCWS - Pacific Cruisers - 49ers
 
We sell lot of these Patterson Block of plate kits.
We also supply the Electric choke which you'll need along with the plastic
electrical connectors.

> Do yourself a favor and stop reading the "hot rod Oldsmobile forum".
> 455 Oldsmobiles used in GMC"S have a huge load on them compared to a
> 4-4-2 or a Cutlass Supreme or a Toronado.
> The exhaust gasses from a GMC are much greater in volume as well as
> temperature, due to the 12,000 pound weight of the coach. The coolant and
> oil temperatures are much hotter as well. These extremes are what Crack
> manifolds.
> Jim Hupy
>

>
> > Since manifold cracking is a common problem on our application, I have to
> > wonder: Is it a problem with the lower profile manifolds? Is it common on
> > Toronados?
> >
> > I dont remember hearing about it being a common olds V8 isssue across the
> > board.
> > --
> > 76 Glenbrook
> >
> > _______________________________________________
> > 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
>

--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk
http://www.appliedgmc.com
1-800-752-7502
 
So I probably did not do enough research on this subject I'm confused about the difference between the "Patterson" block off and something I just
bought from Jim B in Florida with stainless steel plates and a mr. Gasket gasket. Are they the same thing? Did I just throw money away looking for
some answers I have a 78 403. That lost some coolant overheated and I am in the process of replacing the head gaskets and the intake gaskets and I'd
like to reduce the Heat looking for some advice thank you
--
'78 Palm Beach car nut & new to RV'ing
26 ft. 403 OEM wheels, 2 ACs, Pod, ladder, macerator
On FaceBook as David Martin Servati
585-953-53OO call or text
 
Dick's gaskets are thinner then mr gasket I believe. I used mr gasket which will work fine for you. Some folks prefer the thicker gaskets some prefer
the thinner ones. If your hands have been surfaced thicker may be better.
--
Roy Keen
Minden,NV
76 X Glenbrook
 
How does one install the block off plates do they "glue" onto the gasket or do they "glue" onto the intake manifold and the gasket goes over that?
--
'78 Palm Beach car nut & new to RV'ing
26 ft. 403 OEM wheels, 2 ACs, Pod, ladder, macerator
On FaceBook as David Martin Servati
585-953-53OO call or text
 
Jim K - I'm putting together a list and will give Nick a call.

> Dick's gaskets are thinner then mr gasket I believe. I used mr gasket which will work fine for you. Some folks prefer the thicker gaskets some
> prefer the thinner ones. If your hands have been surfaced thicker may be better.

I have 70 years of surfacing my hands. Does that mean I need the thicker gaskets? :roll:

--
Patti & Jerry Burt
73 Gmc 26' Canyon Lands -
Photos - http://jburt.smugmug.com/GMC-Motorhome
Lots of upgrades but lots to do to make it ours.
Members: FMCA - GMCMI - GMCWS - Pacific Cruisers - 49ers
 
There is nothing wrong with a thicker gasket as long as the plate seals
properly.
David, we recommend using a High Temp sealant around the plate and blue or
black sealant around the water passage.
I tend to over torque the intake manifold to assure good seal.

> How does one install the block off plates do they "glue" onto the gasket
> or do they "glue" onto the intake manifold and the gasket goes over that?
> --
> '78 Palm Beach car nut & new to RV'ing
> 26 ft. 403 OEM wheels, 2 ACs, Pod, ladder, macerator
> On FaceBook as David Martin Servati
> 585-953-53OO call or text
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk
http://www.appliedgmc.com
1-800-752-7502
 
> > How does one install the block off plates do they "glue" onto the gasket or do they "glue" onto the intake manifold and the gasket goes over
> > that?
>
>
>
> SteveF has a great photo album on rebuilding a 455 .. look at this photo about the SS block of plates.
> He glues them to the head.
>
> http://www.gmcmhphotos.com/photos/olds-455-engine-rebuild/p1238.html
>
> Hope this helps.
>
> Dennis


Thanks for SteveF's link Dennis. I had forgotten about it.

--
Patti & Jerry Burt
73 Gmc 26' Canyon Lands -
Photos - http://jburt.smugmug.com/GMC-Motorhome
Lots of upgrades but lots to do to make it ours.
Members: FMCA - GMCMI - GMCWS - Pacific Cruisers - 49ers
 
Weight is a factor,but the air drag is also a great load that is there

Get Outlook for iOShttps://aka.ms/o0ukef
________________________________
From: Gmclist on behalf of James Hupy
Sent: Tuesday, April 11, 2017 2:36:03 PM
To: gmclist
Subject: Re: [GMCnet] Intake crossover repair

Do yourself a favor and stop reading the "hot rod Oldsmobile forum".
455 Oldsmobiles used in GMC"S have a huge load on them compared to a
4-4-2 or a Cutlass Supreme or a Toronado.
The exhaust gasses from a GMC are much greater in volume as well as
temperature, due to the 12,000 pound weight of the coach. The coolant and
oil temperatures are much hotter as well. These extremes are what Crack
manifolds.
Jim Hupy

> Since manifold cracking is a common problem on our application, I have to
> wonder: Is it a problem with the lower profile manifolds? Is it common on
> Toronados?
>
> I dont remember hearing about it being a common olds V8 isssue across the
> board.
> --
> 76 Glenbrook
>
> _______________________________________________
> 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
 
455 Oldsmobiles used in GMC"S have a huge load on them compared to a
4-4-2 or a Cutlass Supreme or a Toronado.
The exhaust gasses from a GMC are much greater in volume as well as
temperature, due to the 12,000 pound weight of the coach. The coolant and
oil temperatures are much hotter as well. These extremes are what Crack
manifolds.
Jim Hupy

I don't.
I agree its a far higher load. However , I dont recall a problem with cracked intakes on SOBs with chevy 454s which have even heavier loads and far
worse aerodynamics. Do they have a heavier cast manifold?
I dont recall them looking much different than passenger or truck manifods other than the 'Peanut port' size.
Exhuaust manifolds are another story entirely.
--
76 Glenbrook
 
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