can intake manifold gasket leak cause bad mileage?
Tom
driven very little and has only 15K miles on it. Not a typo, that's fifteen
thousand miles in a 2002.
No work has been done recently. No engine work ever, AFAIK.
Last fall I noticed that my mileage had dropped from 23/33 to 14/27 mpg.
Last week, I lifted the hood to see if I could spot any loose or broken vacuum
lines, and I noticed that the lid of the coolant reservoir was off. The
reservoir was empty - I don't know if it had evaporated out the top, or if
there is a leak.
I have good power when I step on the gas. No odd noises. I haven't spotted any
leak. But I'm in the northeast and haven't been looking much, seeing as how
it's winter.
I just became aware of how dexcool can cause the Lower Intake Manifold gasket
to fail, and the now-expired class action suit. I don't suppose there's any
way to know what percent of 2002 Century will fail.
And btw, how do I get the LIM checked? Would any mechanic have a simple/easy
check that they would do for free? Thanks.
Tom
holy cow, on closer look: what I'd thought was a low level of coolant on this
slim-style reservoir is actually right on the 'Cold' line. The reservoir
should be mostly empty, with just a few inches of coolant on the bottom. The
coolant in there looks dark, but not thick. The radiator cap is clean, and
there is only a bit of sludginess floating on top of the visible coolant.
That's good news.
Also, the engine oil itself is not milky, and the level is not overfilled (so
coolant had apparently not gotten into the oil).
So I guess I should go with a flush and fill. But should I use Dexcool or
switch to something else like the Prestone Long Life? I've read about that for
hours yesterday and there doesn't seem to be a conclusive answer.
One big question occurs to me: do I not have a problem at this point because
of the low miles (15K)? If so, why don't the years matter (since late 2002)?
Also, I still have the problem of the sudden reduction in mileage...
Scott Dorsey
>
>And btw, how do I get the LIM checked? Would any mechanic have a simple/easy
>check that they would do for free? Thanks.
Have a competent tech plug a scanning tool in and look at the fuel injection
parameters... if something is leaking on the intake, it'll show up with some
goofy numbers.
A can of WD-40 or an unlit propane torch can help find the problem.... if
you get it near the leak and it sucks it in, the engine will race.
I doubt anyone will do anything for free today, and I wouldn't trust anyone
who did. If they're not charging you anything for diagnosis, they're damn
sure going to find _something_ to charge you for.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Scott Dorsey
>So I guess I should go with a flush and fill. But should I use Dexcool or
>switch to something else like the Prestone Long Life? I've read about that for
>hours yesterday and there doesn't seem to be a conclusive answer.
If it's not broken, don't fix it.
If you haven't had any problems with the DexCool (and I'm surprised you
haven't because everyone else pretty much has), keep using it and don't
change it.
If it has never been flushed in eight years, it's way overdue. I'd consider
brake and maybe even transmission fluid too.
Vic Smith
>Tom wrote:
>> I have a car with dex-cool (Buick Century 2002 3.1 V6). The car has been
>> driven very little and has only 15K miles on it. Not a typo, that's fifteen
>> thousand miles in a 2002.
>>
>> No work has been done recently. No engine work ever, AFAIK.
>>
>> Last fall I noticed that my mileage had dropped from 23/33 to 14/27 mpg.
>>
How are you measuring that? Are you sure?
I don't know about the Dexcool because I've avoided it, and heard it
causes problems. But I've read that turbulence has some effect, so
the more miles the more turbulence.
My '97 Lumina 3.1 had Dexcool in it when I bought it with 105k miles.
Now has 150k miles. Here's what I did when I bought it.
I drained the Dexcool out by pulling the lower rad hose. Put hose
back, filled with water and ran it hot for a while. Think I opened
the rad petcock and used a garden hose to keep it topped off for a
while. Didn't get too anal about it. When there was no yellow left I
was done.
Pulled hose again to drain, then put on new hoses and thermostat.
Filled with a 50/50 of the Prestone green stuff, and added a pack of
the GM cooling system sealant pellets.
5 years ago. So far so good.
>Also, I still have the problem of the sudden reduction in mileage...
>
First make sure your milage check is accurate.
32mpg is near tops for highway on mine. I never checked city closely
- too many variables. Seem to get around 18-20.
You might have a miss somewhere, or a bad injector.
Hard to tell. If they are original plugs/wires you should replace
them. I'd do the wires first. Plugs might be fine.
Might be worth it to have a mech hook it to a diag machine.
Eliminate the guesswork.
--Vic
ps Sorry I sent a reply to your e-mail.
Steve W.
> holy cow, on closer look: what I'd thought was a low level of coolant on this
> slim-style reservoir is actually right on the 'Cold' line. The reservoir
> should be mostly empty, with just a few inches of coolant on the bottom. The
> coolant in there looks dark, but not thick. The radiator cap is clean, and
> there is only a bit of sludginess floating on top of the visible coolant.
> That's good news.
>
> Also, the engine oil itself is not milky, and the level is not overfilled (so
> coolant had apparently not gotten into the oil).
>
> So I guess I should go with a flush and fill. But should I use Dexcool or
> switch to something else like the Prestone Long Life? I've read about that for
> hours yesterday and there doesn't seem to be a conclusive answer.
>
> One big question occurs to me: do I not have a problem at this point because
> of the low miles (15K)? If so, why don't the years matter (since late 2002)?
>
> Also, I still have the problem of the sudden reduction in mileage...
>
The problem in the mileage reduction could be due to a LOT of things.
Sitting that long the interior of the muffler could be rotted and
blocking the system, Mouse may nave gotten to the wiring and caused
problems. Fuel lines may have developed a leak due to rust. Injectors
may be clogged due to crap in the fuel lines from sitting.
Low mileage is NOT really a good thing sometimes.
As for the Dexcool. Change it out and flush the system and put in fresh
coolant. The bad rap that Dex gets is NOT due to the coolant itself. It
was due to how it was marketed by GM. They claimed it was a lifetime
coolant when it really isn't. It still needs to be changed out and the
system flushed every 4-5 years to prevent problems.
Personally I use the universal type coolant Prestone sells. Then just
note that it will need a flush and fill in 3 years. When you look at
what it costs to do a flush and fill versus what it costs to replace
plugged or damaged parts it's REALLY cheap...
Oh and my usual routine on my vehicles is to drop the coolant, flush the
system. Then while clean water is in the system, pressure test it for
leaks. Drain everything including the block. Then change the thermostat
and the water pump out, inspect the hoses close and every second flush
replace them, new serpentine belt as well.
Being that I keep vehicles a LONG time this is just cost of ownership.
--
Steve W.
cuh...@webtv.net
http://www.prestone.com
http://www.barsproducts.com
cuhulin
Steve
>
> So I guess I should go with a flush and fill. But should I use Dexcool or
> switch to something else like the Prestone Long Life?
Prestone long life and Preston "all makes all models" are just DexCool
clones and contain the same chemical (2EHA) that is in DexCool and
softens intake gaskets.
If you want to be really safe, you should have the lower intake gaskets
replaced anyway. DexCool has already attacked them, and from my reading
I gather that they tend to fail on those engines eventually pretty much
no matter what.
As for alternative coolants, G-05 seems to be the best/safest
alternative to DexCool. Zerex sells it (gold bottle- sometimes hard to
find) and you can get it from any Ford dealer (Motorcraft Premium Gold)
or from any Chrysler dealer (Mopar G-05, which is dyed red instead of
gold like Zerex and Motorcraft). I also hear good things about Peak
Global Lifetime coolant. You could also use old-style conventional
silicated coolant and change it every 2 years like the old days. But it
is getting very hard to find now also.
Steve
> Prestone and Bar's Leaks.That is what I always use.
> http://www.prestone.com
You do realize that Prestone completely changed formulas a few years
ago, right? They don't make a conventional coolant any more, only their
"all makes all models" coolant, and it is a clone of DexCool.
cuh...@webtv.net
Wintertime.Years ago, some people used to change radiator fluid twice
each year.For Summer time and Winter time.
cuhulin
Steve
2-ethylhexaonic acid to keep dissolving gaskets every year.
cuh...@webtv.net
clunkers I have owned over the years, since 1957, in 1957, that old car
was a secondhand car too.I don't remember which brand name of car it
was, it was about six years old when I bought it in 1957.I will keep on
using Prestone, Bar's Leaks too.
cuhulin
Steve
So if you'd always bought Borden milk, and then one day Borden started
selling milk substitute made from manufacturing waste instead of cow's
milk, you'd just keep buying Borden?
The whole point is that Prestone isn't Prestone anymore. I used it
exclusively from the 60's until the formula changed, but I don't use it
anymore. If you want to stick your fingers in your ears and shout
"LALALALALAICANTHEARYOU" go right ahead.
Vic Smith
What you said about the green Prestone being almost the same as
Dexcool was news to me.
What does that mean for eating gaskets, if that was a real problem
with Dexcool?
I've always removed the Dexcool more because it always looked sludged
up than for any other reason.
Does the Prestone green do this too?
I think I've read that's it's mostly exposure to air in vented
overflow tanks that cause the sludging.
I still have those tanks on my cars, but tell the truth, I don't
change the anti-freeze much after the initial hose/fluid/thermo
replacement I do when I buy a new used car.
Might add some because I do a water pump.
Usually only have a car 5-10 years because it rusts out.
The overflow tank on my Lumina looked nasty when I flushed out the
Dexcool, and is still stained, but I haven't looked inside for a few
years. I think I'll check it.
--Vic
Steve
> On Thu, 25 Feb 2010 09:32:48 -0600, Steve <n...@spam.thanks> wrote:
>
>> cuh...@webtv.net wrote:
>>> I never have had any gasket problems (Knock on Wood) with the many old
>>> clunkers I have owned over the years, since 1957, in 1957, that old car
>>> was a secondhand car too.I don't remember which brand name of car it
>>> was, it was about six years old when I bought it in 1957.I will keep on
>>> using Prestone, Bar's Leaks too.
>>> cuhulin
>>>
>> So if you'd always bought Borden milk, and then one day Borden started
>> selling milk substitute made from manufacturing waste instead of cow's
>> milk, you'd just keep buying Borden?
>>
>>
>> The whole point is that Prestone isn't Prestone anymore. I used it
>> exclusively from the 60's until the formula changed, but I don't use it
>> anymore. If you want to stick your fingers in your ears and shout
>> "LALALALALAICANTHEARYOU" go right ahead.
>>
>>
> What you said about the green Prestone being almost the same as
> Dexcool was news to me.
> What does that mean for eating gaskets, if that was a real problem
> with Dexcool?
I haven't found anything really definitive, and it will probably be hard
to do. DexCool was manufacturer supplied, and lots of its issues cropped
up under warranty. Prestone is aftermarket, and there's not nearly such
a good information gathering system on it. But it DOES contain 2-EHA,
the acid implicated in damaging (not really eating, just
plasticizing/weakening) intake manifold gaskets on GM cars. It may also
be prone to sludge formation in air, but its also possible that other
additives in the Prestone keep it from doing that.
Personally, I don't believe in anything that says its "ok for all makes
and models." That means its not really *right* for any make or model :-p
As for DexCool alternatives, Mopar/Ford/Zerex G-05 seems to be very safe
and effective, but that's also based on anecdotal evidence. Some
evidence exists that the "Asian vehicle" coolants (phosphated OAT
chemistry) might work well too, but you have to be careful because some
of *THEM* contain 2-EHA. G-05 does not. Another coolant that is often
recommended is Peak "Global Lifetime," but its somewhat hard to find and
often confused with their "long life" coolant, which is a different
chemistry and is also similar to DexCool. Lots of good debate (and
information buried in the debate..) can be found on the cooling system
fluids/additives section of the bobistheoilguy forums.
The other bottom-line fact is that DexCool seems to be just fine once GM
got all the requirements sorted out- it should only be used in cooling
systems where the overflow tank is pressurized and not with the more
common type where the overflow tank is open to air with only the
radiator being pressurized, and it should only be used with specific
types of gaskets if the gasket ever touches cooling passages. If those
conditions are met, people rarely seem to see an issue with it.