I bought a 68 firebird 400 about 4 years ago. It is a great car but has some minor issues. The biggest issue that I just cant seem to solve is that it has run hot since the day I got it. It has an original 1968 400 block that has been refreshed so it runs like a clock except for the annoying tendancy to overheat. It has a 195 deg. thermostat and a clutch fan with the full cowl (I think). The first thing I did when I got it was replace the original radiator with a new 4-core. That got it to the point of semi-drivability if I drive it on cool days and baby it. Max speed on the highway is about 70. Anything faster and the temp creeps higher than I like (>210 deg.). If I do a jackrabbit start with a warm engine the temp instantly climbs 15 deg to 210+. I am pretty sure the fan is working. It turns when the engine is running. I am running 50/50 water to antifreeze so the mix should be ok. Is it possible that the coolant channels in the block are clogged up with junk? It did have the original radiator in it when I bought it and that old radioator was pretty nasty. Any ideas? I am getting kinda desperate... The car is pretty but it isnt much fun to drive.. A couple days ago I drove it down to the liquor store and the temp kinda got away from me. It was running 220 when I put my eyes back on the temp gauge. I got it home at 210-220 by coasting as much as possible, pulled in the drive and shut it down. I could smell some hot toasty rubber. Does anyone think I did damage???
Start with trying a 180 degree t-stat. Check the clutch fan for sure and about 1.5" should sit outside the shroud.
Have you the rad filler pieces in and the 400 air baffles?
Have you checked your water pump? could be rotted away...check for flow but there are a lot of good threads on W/P's here as well and how to increase the flow and efficiency.
Late and tired tonight but I'm sure others will help as well.
Lots of these little things all add up to a cool running engine...
If the fan clutch is even questionable I would replace it. I just picked one up off ebay for about $35. I 2nd the 180 t-stat. And yes check your water pump.
Like Dave said, change the Thermostat, you're in Colorado, altitude changes the boiling point, also reverse flush the block and heater core, pull the stat out, hook a garden hose to the top hose, pull the lower hose and back flow it. Go back and forth, straight flow, back flow several times to clean the block. Also check the radiator out and make sure crud from the block isn't in it if the original was as bad as you say.
Probably wouldn't hurt to change the water pump and check behind it, the divider plate might also be bad and the bypass might be clogged. All in all about a days work to do all this, but you'll know it's as clean as possible without a tear down.
Up to you if you want to try and pull the block drains, iffy getting them out without breaking on an old engine, but reverse flush should get most of it out.
Wanting a Custom fit in an off the rack world.
I don't have time for a job, I just need the money.
If all else fails, an aluminum radiator will probably solve your issues unless you have too much gunk built up inside the engine water jackets that is not solved with a good flushing.
You are not alone, these cars have a reputation for running hot which is why the factory installed all the baffling plates (upper and lower) and rubber fill pieces to direct all the airflow through the radiator that they could.
2012 Mustang Boss 302 #1918, Competition Orange. FGF replacement 2006 Mustang V6 Pony, Vista Blue. Factory ordered. 2019 BMW X3 (Titled to the wife, but I'm always driving it for her. So I'm claiming it) Old projects, gone but not forgotten: 1967 FB 400, original CA car. After 22 years of work, trashed by the guy who was supposed to paint it. I had to sell it. 1980 Turbo Trans Am 1970 Mustang fastback, 351C 4Bbl, auto 1988 Mustang GT, 5 speed 1983 F-150 4x4, built 302 1994 Chevy K2500 HD 4x4, 454 TBI
What should be the expected operating range of these engines?
I would think the lower would be the thermostat temp (190F stock - test within 187-193F to start to open).
Although the Service and Diagnostic Manuals don't provide specs for top operating temperature, they mention a few temps of various component triggers:
The idiot lamp doesn't illuminate until 246-250F. The TVS doesn't advance timing until 230F. The thermostat should be fully open by no more than 222F.
So my question to those with much more engine cooling system expertise then me: Is 210-220 bad? Us guys with just idiot lights don't know the difference anyway.
And Rockman, if you want to lower the temp a little in a pinch, you could try to dissipate some by turning your heater on full. It may be miserable but can help reduce engine heat.
Thanks guys. That helps. Lots of fun projects to try! When I got the car I pulled the radiator hoses off, stuck them in buckets and cranked it to see if the water pump was working. The pump did circulate fluid but I didnt have any good way to check flow rate, etc. I might as well swap out the pump if I am going to go through the effort to take everything apart as a new OEM is about $80 bucks online. I didnt know you could flush the block. I will definitely try that! My guess is the block is full of crud from the old rad.
I dont know if I have all the the baffling plates in or not. Honestly I dont know what it is supposed to look like. I have a big plastic shroud that goes all the way around the fan and comes in about 4" from the radiator just beyond the inside edge of the fan blades and there is an extra plate ontop that covers the entire top of the fan (I thought the top plate was to keep you from dropping stuff in the fan). Are there supposed to be more plates/shrouds? My service manual just shows the plastic shroud that I have which leads me to believe that the previous owner stuck the top plate on himself.
Thanks guys. That helps. Lots of fun projects to try! When I got the car I pulled the radiator hoses off, stuck them in buckets and cranked it to see if the water pump was working. The pump did circulate fluid but I didnt have any good way to check flow rate, etc. I might as well swap out the pump if I am going to go through the effort to take everything apart as a new OEM is about $80 bucks online. I didnt know you could flush the block. I will definitely try that! My guess is the block is full of crud from the old rad.
Be VERY VERY careful about a new water pump. As many in the Pontiac hobby have found out the hard way - you want a pump with the original style cast impeller, NOT the cheep stamped steel impeller.
You will have to go out of your way to get the good one, and ordering on-line is a great way of getting the wrong one. Some have gone to good parts houses like NAPA and had to go through the entire store's supply to find a cast impeller. Or go straight to a good Pontiac repro parts house like Ames who only sells cast impellers.
2012 Mustang Boss 302 #1918, Competition Orange. FGF replacement 2006 Mustang V6 Pony, Vista Blue. Factory ordered. 2019 BMW X3 (Titled to the wife, but I'm always driving it for her. So I'm claiming it) Old projects, gone but not forgotten: 1967 FB 400, original CA car. After 22 years of work, trashed by the guy who was supposed to paint it. I had to sell it. 1980 Turbo Trans Am 1970 Mustang fastback, 351C 4Bbl, auto 1988 Mustang GT, 5 speed 1983 F-150 4x4, built 302 1994 Chevy K2500 HD 4x4, 454 TBI
Don't forget to check/change the radiator cap as well. A bad cap at higher altitude will send temps up. Is there a coolant recovery tank? And like Jim said, if all else checks out, 210 running down the freeway is not terrible, 220 is pushing it a bit though. We just had a 105 plus day here in Sacto last week and sitting at a drive through in my 03 honda, the A/C started feeling warm, looked at the gage and it was at 3/4(below 1/2 is normal)popped the hood and no pressure in the upper hose. New cap, problem solved.
Block offs go between the front bumper and radiator core support. Fills in that big hole on each side of the hood latch. Underside baffle isn't as important but definitely would help.
Water pumps are hit and miss finding a cast impeller, I've run both without issue though. Just make sure whatever you get doesn't scrub the divider plate. Once you pull the pump make sure the plate is in good shape, also you'll see two tubes that go from the divider into the Timing cover, check them for condition and that their rubber O ring gaskets are in place.
Simple stuff, but if you haven't worked on a Pontiac it's just one more quirky thing about them.
Wanting a Custom fit in an off the rack world.
I don't have time for a job, I just need the money.
would a bad rad cap leak fluid? or is there some other way to see that it is bad? No blow-off tank. The overflow is just a tube that runs down the front of the radiator and ends just above the bottom of the bumper. Good call on Ames. They have water pumps for $35 bucks which is hard for me to believe so I will call them to make sure it is the right one.
Looks like I am missing the lower baffels. Would these be "Core Support Filler Panels"? from the ames catalog. $99 a set..
Thanks again for the guidance. These old pontiacs seem to specialize in quirky!
Also a good call from Jim on turning the heat on temporarily. I saw that in a movie years ago (John Candy) and always wondered if that works. Unfortunately the heater in my bird doesnt work. The fan controls in the dash are junk and there just for looks. The interior needs some help but that is a project for another day... The important gauges work, the key turns, and the pedals work. Especially the gas! So 220+ is not bad. Maybe I need to revise my interpretation of "high temperature". Phew! I thought I did some damage! My manual says the stock (190deg) stat should be fully open at a temp not in excess of 222deg (their wording not mine). So I was assuming about 220deg was as hot as you would want to see. 220 is about where I start getting radiant heat burns on my feet too so I am good with <220 or I cant drive in sandals.
I am in Broomfield so probably not too far from you. I have been planning to join a firebird/camaro club. Now that my daughter is out of diapers I have more time for other stuff. The firebird has been out of the garrage a whole 3 times this year! I have heard rumors of a north-denver club but havent met anyone in it. Are you in one Colorado68?
I will post some pics later tonight for you all to check out.
220* is a bit on the high side. I'm running 185 down the freeway but climbs to 200/205 ideling around town so have been spending quit a bit of time working on fixes to lower that temp. If you get a new pump, check the divider distance between the impeller vanes and the divider. You'll want to bend it inward to .060" clerance. No more than .10 clerance or your pump isnt working as it should. Also, get the one with a cast impeller. The filler panels you mention are the uppers. The lower is a single piece baffle. The only aftermarket ones are fiberglass. Check your fan clerance in the shroud, should be 2/3 into the shroud. Have you confirmed that your gauge is accurate? You can try an infrared thermometer to make sure. Not in a club and about 10 miles from you down Indiana. Feel free to PM me and we could meet up sometime.
I ordered a new water pump and fan clutch from ames. They should be in on friday. I called ames before I bought and confirmed that the water pump they are selling for $35 bucks has the old style cast impellor (it does). I also ordered a few other goodies. You cant beat ames pricing!! I found a 180 T-stat locally and changed it out. Temp rise was slower with the new t-stat but still topped 220 sitting in the drive. My guess is the waterpump and/or fan clutch is shot as everything else seems ok. I will know this weekend!
Has anyone replaced their front to back fuel lines? Mine are a hodge podge of steel line sections hose clamped to rubber hose sections all of which are clamped or wire tied to seemingly random attachment points. Ames has great prices on front to rear fuel lines and the proper OEM clamps and hangers. But I am having trouble finding some sort of drawing that shows how the lines should be routed and where the clamps go. My chiltons and service manual are not helpful. This will be my next biggish project as I am sick of fuel leaks.
I cant make the 1st gen cannonball run in estes. But I am planning on bringing the bird down to the classic car/airplane show at the front range airport on aug 21. I go every year becuase the show is free (I only enter free shows) and its for a good cause. Plus you get lunch and a ticket into the beer garden if you bring a car or airplane! I dont know if I can post links to this forum. I am guessing not. So PM me if you are interested and cant find it.
...Once you pull the pump make sure the plate is in good shape, also you'll see two tubes that go from the divider into the Timing cover, check them for condition and that their rubber O ring gaskets are in place...
Woh there big fella! There are no tubes or O rings in a '68(8 bolt) set up. Also, the '68 (8 bolt) set up has 2 divider plates(see below)... You will most likely have to work on one of the plates to reduce the clearance to the waterpump impellor...VERY IMPORTANT!
Post some photos so we can see your full set up. That will help tremendously.
Last edited by Bronze Bird; 07/28/1003:26 PM.
I'm a hobbyist. Not a professional. Don't be hatin'!
I want to know more about those tubes and o-rings too Greg!
Rockman, we have all been there worrying about the water temp in our birds, so join the club! On days where its above 90 degrees here I don't even bother driving the bird because if I get caught in a traffic jam my bird would burn up. As long as its in the 80s or lower I can get by using the electric radiator fan.
'68 428 HO M3 Monster, 4-on-the-floor! Need I say more?
My cooling issues seem to be resolved. The change that put me over the edge (or under the temp) was using a smaller diameter water pump pulley from an AC equipped car. My original pulley was 8" in diameter...replaced with a smaller pulley from a later model car...had to make a 7/8" spacer to fit under the pulley with the 8 bolt set up. Keep in mind, my engine is far from stock anymore.
Will be glad to help anyone considering this...will even cut a spacer if you provide parts.
I'm a hobbyist. Not a professional. Don't be hatin'!
Overdrive and underdrive pulley systems are available from RARE in Billet Aluminum if you really don't care about original.
...not for the '68 and earlier 8 bolts. I looked high and low. You have to switch over to the 11 bolt timing cover/waterpump if you want to use the billet stuff.
It seems most use the 11 bolt covers anymore. KRE just came out with a replacement 8 bolt cover within the last year or so. $175!!!
I'm a hobbyist. Not a professional. Don't be hatin'!
From Bronze Birds Pic I'd say my fan is positioned too far forward. The backs of the blades are about even with the edge of the shroud.. A smaller pulley makes sense as smaller fan pulley would make the fan turn faster. My fan pulley is a standard 8". It also appears that my fan is non-standard too. I have a 6 blade fan. According to my service manual it should have either 4 or 7. Argh. no wonder things dont work quite right.. So what is the advantage of 11 bolt covers over 8?
Seems like most people do not have their fans installed correctly as far as depth. Ideally, half in, half out is how they are supposed to be. Makes a HUGE difference in cooling!!!
You're running an 11 bolt pump, make sure all the correct parts are in there. You're heater hose is incorrect as well, it should tie into the back of the PS cylinder head, not that it'd make a huge difference but...
11 bolt seems to be more consistent cooling, although you'll get arguments on that. Loose the sheetmetal shroud and get the fan positioned right. Can't tell for sure but it looks to small a dia or not centered for the plastic shroud opening.
And it looks like you're 1:1 crank to WP pulley, an overdrive (smaller on the WP) would definitely help. Probably be easier to find a two groove pulley.
Wanting a Custom fit in an off the rack world.
I don't have time for a job, I just need the money.
What should be the expected operating range of these engines?
I would think the lower would be the thermostat temp (190F stock - test within 187-193F to start to open).
Although the Service and Diagnostic Manuals don't provide specs for top operating temperature, they mention a few temps of various component triggers:
The idiot lamp doesn't illuminate until 246-250F. The TVS doesn't advance timing until 230F. The thermostat should be fully open by no more than 222F.
So my question to those with much more engine cooling system expertise then me: Is 210-220 bad? Us guys with just idiot lights don't know the difference anyway.
And Rockman, if you want to lower the temp a little in a pinch, you could try to dissipate some by turning your heater on full. It may be miserable but can help reduce engine heat.
Drove my 1st FB for a year with the original radiator, 4 blade fan, no air baffles. And replacement 195 stat. Had 90K miles when i installed gauges and found it was run'n 210-215. Up to 220 sometimes.
The fan that solved my 7 year hot issue was 19.5" from tip to tip, 7-blade, clutch fan. If you ever go milling through a bone yard this exact fan came on MANY GM vehicles, we've found them on mid 80's V-c w/ a/c on Camaros. Also on most ALL full size GMC vehicles etc. And yes, the 19.5" 7 blade clutch fan does fit inside a stock shroud on FGF...
"It has an original 1968 400 block that has been refreshed..."
"You're running an 11 bolt pump, make sure all the correct parts are in there."
I think HO is correct. At some point, your timing cover, water pump, and possibly the pullies have been "updated". Not a bad thing at all. Just makes it a bit more challenging to put together the right parts.
I'm a hobbyist. Not a professional. Don't be hatin'!
Well I ordered the wrong water pump and backer plates... I ordered the 8 bolt since the catalog stated "1968 8-bolt water pump" and "1969 11 bolt water pump". I also tried to count the bolts standing on my head with a flashlight and apparently counted exactly what I thought should be there (8). I already re-ordered the 11 bolt pump and plates. The 11-bolt cost $1 buck more than the 8-bolt. The wife is going to love my credit card bill this month!
My fan has a diameter of 18" tip to tip. I could definitely fit a 19" or slightly larger as I have about 1-1/2" of clearance between the tips of the fan blades and the shroud. Salvage yard sounds great to me as a new fan runs $110 bucks.. Thanks for the tip!
Take it slow and easy on that credit card. If you overdue it, the wife will always blame it on the bird.
Take it slow, and allow her to be seen in the bird around town as you work through the various car issues. She will definitely notice everyone is looking at her (or the car) as you make your way about town, and she will graciously enjoy the positive attention.
If you don't keep it positive, the wife could turn to never liking the bird due to money matters. The FGF Bird is one of the sexiest cars ever made, and people notice it immediately. Your wife will probably enjoy the attention.
'68 428 HO M3 Monster, 4-on-the-floor! Need I say more?
Hey do you guys know if the 11 bolt water pump would be the 11-bolt for early 69 cars (ames FN257D) or the 11-bolt pump for all V8s 1969 to 1979 (ames FN257H)? There are no pictures so I cant tell that way and my service manual/chiltons are no help... I googled around to try to find pictures or descriptions but to no avail...
You are right about the gradual approach on parts purchases. I cant have the wife mad at the bird! I am working on taking that stainless shroud thing off tonight (gotta file off all the dang rivets) so I should have better pics later on.
The difference is going to be in the length of the shaft the fan bolts to. I just went through all this putting my engine together. The early ones are short shaft and the later are longer. You will have to measure yours or none of your belts will line up. Another Pontiac thing!
All Pontiacs up to and including 68 used the 8 bolt. Then, all 69-79 went to the 11 bolt pump. In addition, there are two different 11 bolt water pumps. They are referred to as the short (early 69) or long (later 69) water pump. The one you need depends on the pulleys that you have. If you try to use the wrong one, your pulleys will no be lined up. The good news is, if you need the longer one, you can use the short one, you will just need 1/4" spacer that goes behind/inside the waterpump/fan pulley. Whereas if you need the short one and buy the long one, you are screwed...
If I remember correctly one is 3-1/4" vs. 3-1/2". If you are unsure which one you need, always go with the "later" one which is the 3-1/4" because as I stated above, you buy the spacer from almost any parts place (the look like huge washers with all the holes drilled in them for the fan bolts to go through. Most of the times they come in a package of several thicknesses so you can create the thickness you need.
Now here is a trick if you need to use a spacer inside the fan pulley. Put a dab of silicone between the spacer (or spacers if you need more than one) and let it set up before tring to insall because it can be difficult to line up all the holes in the spacers, pulley, fan etc. Just don't use too much as you don't want to creat a "wobble" in the pulley etc.
Here is the problem when it comes to water pumps, pulleys & fans. Over the years people change this stuff around for many reasons and most old Pontiacs end up with the wrong water pump or wrong pulleys. If you look closely at your engines pulleys and they do not line up absolutely PERFECTLY, I gurantee you someone along the way changed to the incorrect water pump ie: 8-bolt converted to 11 bolt and or short pump vs. long pump or vice versa.
Any of this can lead to running hot, throwing belts, wearing out water pumps and or alternators etc. A misaligned belt can cause lots of problems. This is what prompted me to round up all the correct parts for my 68. I went back to the 8-bolt water pump, correct pulleys etc. and once I did my car no longer through belts under high RPMs, everything lined up dead nuts and everything worked as it should! It's all about having the correct parts & pieces.
In addition to all of the above, people also have converted from the 8-bolt pump to the 11 and did so without out changing and getting the correct divider plates and or the two short little "tubes" that go inside the 11 bolt that are not inside the 8 bolt. So it's easy to see how over the years all of this stuff has gotten so screwed up on these old cars. The thing to do is take inventory on what you have (part numbers off the pulleys etc.), figure out what you should have, then find what you need and put it all back together the correct way and your problems with be resolved.
Vikki has a section of the shop manual on her web site that lists all the correct part numbers for all the pulleys for each year etc. Just be sure to look up the correct pulley as cars with a/c and or power steering etc. can list different part numbers. Look up the pulleys for your exact set up, then post what you need on here, try Frank's Pontiac parts etc. and locate the correct part numbers and you and your engine will be much happier!
Now here is a trick if you need to use a spacer inside the fan pulley. Put a dab of silicone between the spacer (or spacers if you need more than one) and let it set up before tring to insall because it can be difficult to line up all the holes in the spacers, pulley, fan etc. Just don't use too much as you don't want to creat a "wobble" in the pulley etc.
I used super glue. Too many pieces to handle with only 2 hands. Set up everything on a spare water pump on the bench. Bolted up firmly for about 15 minutes to let the super glue set. Unbolted, then installed. Worked perfectly.
I'm a hobbyist. Not a professional. Don't be hatin'!