Conference vmsnet::car$note:carbuffs

    Does anyone have any personal experience with cooling systems on old
    Pontiac V8s?  I have been told by one company selling restoration parts
    and one individual that cooling can be a real problem.  Some of the
    cars came equipped with 3 core radiators (2" thick core) and others came
    with 4 core radiators (2 5/8" thick core).  I have been told not to
    even think about using the 3 core unit.  Well, sure enough, when I
    looked at what I had in the GTO, it was a 3 core.  The former owner
    commented that it always seemed to run a bit hot, about 210 degrees I
    think he said.  However, it also is missing the shroud and the fan
    spacer is too short, so I didn't give the radiator much thought until
    now.  I'm wondering how much of the problem was due to the lack of a
    shroud and location of the fan, and how much of it (if any) was due to
    the radiator itself.  I want to get this right when I reassemble the
    car.  The new 4 core radiator and the necessary adapter kit to mount it
    runs about $255.00, not to mention that it will also cost about $110.00
    for a shroud and a fan spacer.  This is getting expensive.  The
    question is, does anyone know if the 3 core radiator is efficient
    enough when used with the correct shroud and spacer, or is the 4 core
    radiator really necessary?  I want to do the right thing regardless of
    the cost, but I also don't want to spend money needlessly that could be
    used to buy other parts.
    
    Dave  

We ran Pontiac V-8's in Florida in the 60's and 70's with no cooling problems.
I don't know what radiator they had though.

Jim

    Having no shroud, or the wrong shroud will cause you to run hot in
    traffic (sitting still).
    
    I don't think ponitacs "as a rule" have cooling problems.  I think 
    the cooling system isn't set up, or working properly.  Use the standard
    stuff when putting the cooling system on, i.e. good thermostat, make
    sure air is entering the radiator properly to disappate heat, make sure
    you have enough cooling capacity...  etc...
    
    MadMike
    

    While in the USN a friend had a Pontiac Wagon, We had to remove the
    Thermostat, and it still ran hot, it was churning the coolant to foam.
    Foam would not circulate, then we found out the engine (400 CID) was 
    supposed to run at 220 degrees, they presurized the cooling system, so
    the boiling point was raised, however the car was running about 250
    degrees.  I do not know what he did to stop the overheating.
    
    Dave

    The 400 was supposed to run at 220 degrees?!  That sounds damn hot to
    me.  I thought that it should be in the 180-195 degrees range.  Anyhow, 
    I have heard several stories like .680.  Supposedly, the 4 core
    radiator is supposed to be a fix for the problem.  It is just that the
    person who was insisting that I change the radiator was also trying to
    sell me a new one, so he had something to gain by convincing me to
    change it.  I thought that he was most likely telling me the truth, but
    it is a lot of cash that I hadn't planned on spending, and I would feel
    better if I got verification of his claims from others.
    
    Dave 

     I've owned several GTO's

     Human burb, I hit the wrong key.  None of them overheated, the one
    with a/c had a 4 core radiator, the rest of them had three cores.  As 
    stated elsewhere, the shroud is very important, another thing is the
    impeller (sp) I've seen several variables on "rebuilt" pumps, the
    number and width of vanes can vary a lot.  The spacer you are talking
    about, there is more than one pump length, and more than one offset on
    the pulley, the longer pump has an improved bearing. The big difference
    in length I'm talking about is late 69 - early 70.  

>    and one individual that cooling can be a real problem.  Some of the
>    cars came equipped with 3 core radiators (2" thick core) and others came

Auto trans and no a/c you hot the little radiator

>    with 4 core radiators (2 5/8" thick core).  I have been told not to
>    even think about using the 3 core unit.  Well, sure enough, when I
>    looked at what I had in the GTO, it was a 3 core.  The former owner

Manual trans and/or AC and you got the larger radiator.

>    commented that it always seemed to run a bit hot, about 210 degrees I
>    think he said.  However, it also is missing the shroud and the fan

The temp sender's next to the exhaust port.  210 is normal for that type of 
sender arrangement.  If the sender's in the intake manifold it should run 
around 185-190 (with the 180 thermostat)

>    spacer is too short, so I didn't give the radiator much thought until
>    now.  I'm wondering how much of the problem was due to the lack of a
>    shroud and location of the fan, and how much of it (if any) was due to
>    the radiator itself.  I want to get this right when I reassemble the

The fan shroud is a MUST on '78 and later GTOs due to the shape of the 
grille.

>    car.  The new 4 core radiator and the necessary adapter kit to mount it
>    runs about $255.00, not to mention that it will also cost about $110.00
>    for a shroud and a fan spacer.  This is getting expensive.  The

Ain't restoration fun?  :-)

>    question is, does anyone know if the 3 core radiator is efficient
>    enough when used with the correct shroud and spacer, or is the 4 core
>    radiator really necessary?  I want to do the right thing regardless of
>    the cost, but I also don't want to spend money needlessly that could be
>    used to buy other parts.
>    

The three core rad will work fine as long as you have the proper fan 
position and shroud.  If you start monkeying with the carburetion and cam, 
you will want to make sure you keep the vacuum advance on the right port 
(manifold vacuum, not timed vacuum) or it'll overheat in traffic   ...with 
any radiator.

    Your last comment Skip is what has me wondering.  The engine has a
    Crane cam that I would guess is pretty radical by the way it idles, and
    the carb is a Holly 750 CFM dual feed.  I'm definately not dealing with 
    factory stuff here.  It sounds like the existing radiator was OK when
    the car was in it's original form, but at this stage, the 4 row core may
    be a good idea.
    
    As for the difference between the radiators in the A/C and non A/C
    equipped cars, the difference is in the length of the core, not the
    number of rows.  The non A/C cores are 15 1/2 inches, and the A/C cores
    are 17 1/2 inches.  Both lengths were made with the 3 and 4 row cores.
    The two lengths are not interchangable (not without using a torch
    anyhow) due to the shape of the core support.  The 3 and 4 row core
    units of the same length are interchangable by removing 6 bolts and 
    changing the 3 mounts, so it is a simple swap.
    
    Dave

If you can't pull enough vacuum to advance your timing, it'll run hot 
because the timing is retarded when you're lugging it through traffic.  If 
the cam makes enough vacuum and you have the hose on the right port on the 
carb, it won't overheat.

    I've probably helped creat a overheating problem...but was wondering if
    anyone might have ideas on curing some of it. I am not partial to
    running over 220 :^) and I like to maintain 180-200.....
    
    I removed my small block and inserted a 30 over 427 and added a 671
    blower.  
    
    The intake has two 1" id feeds for water, replacing the thermo housing
    setup that was on the standard intake.  I've modified the hose setup to
    run these two into a aftermarket thermo housing (180 degree
    thermostat), then connected the upper radiator hose. No shroud (no
    room, no fan).
    
    I used a special (for blower) water pump to stop cavatation, and the
    original (rodded/rebuilt) radiator, and a 1200 cfm electric fan (bladed
    fans don't fit to well :^)) I'm thinking a electric motor on the pump
    would help move the water more consistently through idle/off/varied
    rpms....? And go back to a stock water pump.
    
    The temp climbs from coldstart to 200 in about 10 minutes at idle and I
    have to play games with the fan and try to keep the car moving
    (avoiding red lights) to maintain 210-220.....and not go up to 240....
    I just would like to keep it around 180-190 normal traffic etc.
    
    -rich
    1st blown motor I've ever tried :^)
    

    It's been a while since I've shopped for an electric radiator fan, but
    isn't 1200cfm a little small for that big an engine? 
    
    ...tom

    >It's been a while since I've shopped for an electric radiator fan, but
    >isn't 1200cfm a little small for that big an engine? 
    
    it's a moroso fan and I typo'd it's 1400 cfm.  It pulls a "lot" of air
    through the rad.  I've heard much bigger, and it's not effective - much
    smaller and it won't do much good either.
    I'm going to try the wetter-water additive - see how much it helps :^),
    super chevy's first meet is here in Memphis this weekend...and I've
    got the car entered in the pro class :^)   
    
    -rb

I had a problem with this last summer, but it miraculously went away over the
winter :-) ... My car has been running hot, especially in traffic, but sometimes
on the highway. It has never physically overheated, but the rising needle makes
me very nervous.

The car has ~180K miles on it, so I don't want to spend a lot on getting it
fixed. I had the thermostat replaced last year and the coolant was changed, but
it didn't help. I will probably end up bringing it in pretty soon, but wondered
if there were some simple things I could check first.

Any/all advice appreciated.

-Jeff

Do a leakdown test.  You probably have a partially blown head gasket.  It's
very common on Honda/Acuras.

Jim

    Or do a compression test, which will spot a blown head gasket.
    
    Simple things to check:  Make sure your fan is coming on when it's
    supposed to.
    
    MadMike

>>    Or do a compression test, which will spot a blown head gasket.

It's probably not totally blown.  Honda had problems with head gaskets
leaking.

Jim

    Jim,
    
    Why would a blown head gasket cause overheating in Acuras.  To me
    it shouldn't overheat until the water level gets low.  Maybe that
    is a good question to ask.
    
    Does the Acura require fluid for the radiator on a regular basis?
    
    Rob

>>    Why would a blown head gasket cause overheating in Acuras.  To me

When the engine cools down, it pulls air in from the headgasket area rather 
than coolant from the overflow tank.  You end up with a system that has air
in it, so the head runs hot.  That aggravates the situation until the gasket
finally blows totally which could take years.

Jim

    
    Or air leaking from the cylinders can pressurize the cooling
    system with excess air, with the car running. Either way it
    overheats...
    
    /Pat

The problems been occuring since last summer, but hasn't been much of a problem
over the winter months. It stays right in the middle of the guage during the
colder months. I've never needed to add coolant and I believe that the fan is
coming on when it's supposed to.

I was thinking (but hoping it was not) the radiator.

Thanks for the suggestions.

-Jeff

It could also be the radiator or the thermostat.  I would test (or just 
replace) the thermostat and take the radiator to a shop for a flow test.
You have nothing to lose but some small money.  If those check out, then
it's most likely the head gasket.

Jim

>> The car has ~180K miles on it,

You may also want to try some heavy detergent and a strong reverse
flush on the radiator's outsides.  180K miles allows for a lot of
bugs and dust and little dandelion seeds to plug up the airflow.

FWIW,
Chuck

    My experience is that radiators last about 8 years with no care
    and about 10 years with regular flushing... i.e. a 1987 Integra
    is probably due.
    .02 K

     ditto .699
    
    I'd have the radiator vatted before jumping to conlusions about
    other more complicated causes of overheating.
    
    My FIL had an 88 buick regal that was overheating.  The radiator
    was so stopped up with bugs and grass seed it wasnt getting much
    airflow through it.  8 hours in the vat, and it was clean as
    a whistle, no more overheating.
    
    --Bert
    

You really shouldn't vat a radiator with the plastic tanks.  Pull it out
and wach the exterior with a soft bruch and soap & water.

Jim

    
    I know they had the buick radiator vatted, I wasnt there to pull it
    so I dont know if it had plastic tanks.
    
    None of my vehicles have plastic tanks on the radiator, vintages ranging
    from 1977 - 1996.
                                                                     
    Is this a Honda thing?

>>    Is this a Honda thing?

It's pretty widespread today across cars from the US, Asia, and Europe. Our
Hondas had plastic tanks as well as our Volvos (until I replaced them with
REAL radiators).

Jim

    Even my 89 Ford F150 had plastic tanks.  It's pretty widespread nowadays.
    Of course you can get replacements without the plastic if you want to 
    spend the extra money.  The nice things about plastic is that it won't
    corrode, is cheaper, and it flexes a bit without becoming more brittle.

    Cheers,
    --Dave

How is the plastic tank bonded to the fin assembly?

Jim

>>How is the plastic tank bonded to the fin assembly?

It has little metal fingers that crimp around the edge of the plastic tank.
There is a rubber gasket between the metal core and the plastic tank.  As these
units get older, the gasket shrinks and the metal fingers loosen their
grip on the plastic tank.  Coolant will start leaking when the car is cold 
on very cold winter days.  It will seal right up when the coolant warms the
gasket.  Sometimes you can solve this by re-crimping the metal fingers, 
sometimes you can't.

Jim