Main
Page | Log In | LogOut | Register
My Profile | Active Users | Search

CorvetteforumC3
CorvettesTech
tip: Intake valve deposits cause rough engine

zwede
Senior
Member

2123 posts [100%]
Plano TX

Tech tip: Intake
valve deposits cause rough engine

2:50
PM 7/21/2002

Something we often forget when we're chasing
odd driveability issues is to check for intake valve deposits.
Back when I had a carb I had an intake manifold that leaked on
the bottom, sucking oil into the ports. It wasn't horrible,
about 1 quart every 800 miles. Not enough to foul the plugs,
even.

Then I swapped to EFI and when the intake was off I noticed
quite a bit of sludge on the valves.
I wasn't too happy
with the way the engine ran. Symptoms were:

Off idle hesitation
Part throttle, low rpm
"miss"
Rough idle.
Hard start.

Turned out all this was caused by those pesky intake valve
deposits. I poured several cups of water into the engine, and
then ran deposit remover in 3 tanks of gas.

The difference is amazing. It now idles smooth, throttle
response is great, starts better and is just smoother and more
powerful.

I noticed several forum members have had intake sealing
issues, so after you get it fixed it is a good idea to run
some deposit remover in the tank.

I used prestone concentrate which worked great, but I'm
sure there are other good products out
there.
_______

Markus Strobl

1971 Coupe, LS-5 454, Muncie M20 4-speed. 490 hp, 554
ft-lbs. Red on Saddle.
Edelbrock Aluminum heads, Roller
Cam, Super Comp Headers, Multipoint EFI, 17" Ralleys.
http://www.corvetteforum.net/c3/zwede

Vetterodder
Senior
Member

1866 posts [100%]
Stockton, CA

Re: Tech tip:
Intake valve deposits cause rough engine
(zwede)

8:10
PM 7/21/2002

Good advice Zwede. I've also seen sludge on
engines with rich idle mixtures, especially on those that see
a lot of idling in relation miles driven. While the detergent
package in most gasolines do a good job of keeping the backs
of the valves clean in efi cars, they don't always keep up
with the amount of buildup often seen in carbed engines,
especially those with big cams and carbs.

_______

`65 coupe, 327, 4spd, numbers matching but
lots of mods.
`01 Dakota, 4.7, 5spd, 3.92 limited
slip
`99 BMW 323, 5spd

mrvette
Senior
Member

2002
posts [100%]
Orange Park Florida

Re: Tech tip:
Intake valve deposits cause rough engine
(zwede)

6:22
AM 7/22/2002

It all shows to go you, gotta ditch those carbs
and go to EFI, no other choice in the matter, really....

GENE
_______

http://www.funport.com/mrvette72/

virtue4u
Senior
Member

831
posts [100%]
Houston, Texas, USA

Re: Tech tip:
Intake valve deposits cause rough engine
(zwede)

7:30
AM 7/22/2002

How much water? How fast is the water poured
in? What rpm when pouring in the water? What does the water
do?
_______

[IMG]('http://temp.corvetteforum.net/c3/virtue4u//vettehood2.jpg')
[/IMG]

zwede
Senior
Member

2123 posts [100%]
Plano TX

Re: Tech tip:
Intake valve deposits cause rough engine
(virtue4u)

12:20
PM 7/22/2002

I use 2 cups, each holds 12 oz. I rev the
engine to 2000 rpm and pour in as fast as possible without
stalling the engine. After the last of the water is gone, I
rev it a little higher for a few seconds until it smooths out
before letting it idle.

I wouldn't do it more than once a day for 2-3 days. Some of
the water goes past the rings into the oil. After driving for
10 miles or so, it will boil out of the oil.

The first time I did this, there was a big cloud of
blue/black smoke out the tailpipes. The third time there was
very little smoke. I figure the amount of smoke depends on how
much crap is in the engine.

The water trick will also clean intake ports, combustion
chambers and spark plugs. Unfortunately it does very little
for the exhaust valves.
_______

Markus Strobl

1971 Coupe, LS-5 454, Muncie M20 4-speed. 490 hp, 554
ft-lbs. Red on Saddle.
Edelbrock Aluminum heads, Roller
Cam, Super Comp Headers, Multipoint EFI, 17" Ralleys.
http://www.corvetteforum.net/c3/zwede

flood
Senior
Member

707 posts [100%]
Greeley CO

Re: Tech tip:
Intake valve deposits cause rough engine
(zwede)

12:26
PM 7/22/2002

Im a newbie to all this and pouring water in my
engine sounds awful.

But hey, if you guys say it works. Which to use? tap water
or distilled?
_______

1975 L-48 4 speed
Coupe, 3.70, SS brakes, VB strut rods

zwede
Senior
Member

2123 posts [100%]
Plano TX

Re: Tech tip:
Intake valve deposits cause rough engine
(flood)

12:58
PM 7/22/2002

Distilled would be best. I used filtered water
and it was fine.
_______

Markus Strobl

1971 Coupe, LS-5 454, Muncie M20 4-speed. 490 hp, 554
ft-lbs. Red on Saddle.
Edelbrock Aluminum heads, Roller
Cam, Super Comp Headers, Multipoint EFI, 17" Ralleys.
http://www.corvetteforum.net/c3/zwede

Got79Fever
Junior
Member

17
posts [100%]
Farmington Hills. MI

Re: Tech tip:
Intake valve deposits cause rough engine
(zwede)

1:09
PM 7/22/2002

my daily driver (96 lumina sedan) has this kind
of problem. this solution should work here also? think it
would be tough to get past all the intake sensors. btw, would
water hurt them?

Larry82
Senior
Member

1999
posts [100%]
Missouri City TEXAS

Re: Tech tip:
Intake valve deposits cause rough engine
(zwede)

1:34
PM 7/22/2002

Let me jump in with a question or comment.

I have seen repair shops use the intake, upper cylinder
cleaner that is sucked slowly out of the bottle by a small
hose attached to in intake vacuum, such as the PCV valve, or
the brake booster vacuum.

Does it make sense to slowly introduce the H2O into either
of
those?

» Return to C3
Corvettes

Forum Jump 50th
Anniversary Events Audio/Electronics Autocrossing
& Roadracing Babes Breathless Performance C1 &
C2 Corvettes C1 & C2 Parts
C1s & C2s for Sale/Wanted C3 Corvettes C3 Parts
for Sale/Wanted C3s for
Sale/Wanted C4 Forced
Induction/Nitrous C4 General
Discussion C4 Parts for
Sale/Wanted C4 Tech/Performance
C4s for Sale/Wanted C5
Forced Induction/Nitrous C5 General
Discussion C5 Parts for
Sale/Wanted C5 Tech/Performance
C5s for Sale/Wanted C6
General Discussion Car Care
Products Corvette Accessories
Corvettes of Houston Cruise Control Auto Die Casts
& Collectibles Drag Racing
ECM/PCM Tuning Engine
Mods Exit 28 Motorsports
F-Body General Discussion Factory Correct Resto Great
Lakes Help Forum Ken's Newsletters Kill
Stories LAPD Moderator's Corner Mountain -
Prairie National Events Northeast Off Topic
Other Cars Other
Country Events Pacific Politics & Controversy Regional Coordinator's Forum Southeast Southwest
T Byrne Motorsports Testing West Coast
Corvettes Wheels & Tires
Xtreme Motorsports Z06
Discussion Zip Products Section
ZR1 Discussion

Powered by zeroforum 2.0.4 b1.
©2001 zeroforum.com.

C5
FAQ
CF
C5 Registry
CF C4
Registry
Performance
Reg
Neighbor
Locator
Corvette
Events
Event
Galleries
CF Name
Tags
Product
Reviews
Tech Tips

Home
Pages
Corvette
Portal
Corvette
Clubs
Vanity
Plates
Race
Sites/Tracks
Vendor Sites

Forum FAQ

Moderator
Bios
Advertising

Wuname