455 overheating, help!!
Notice the third application? Hmmmm...And engine coolant IS listed, see number eight.
My first post here and thought this would be a good thread to chime in on.
IMO you have a lot of variables, lots of different things you have tried and possibly multiple causes. Believe me I have been there and I feel your pain. I think you need to go through all the potential causes one at a time and try to break them down as contributors and/or causes.
I think you should address the sitting in the driveway overheating first. Things are easy to test and the engine is under no load so the cooling demand is really next to nothing. I'll ask this question - what are ALL the potential causes of overheating just sitting in the driveway under no load? I'll take a stab and suggest some tests.
1) Air flow
Setup one or two external fans that blow into the radiator and see if this improves things. Take a garden hose and spray the radiator with water. If no change in overheating is observed then your flown may be too low.
2) Coolant flow
Get a IR surface temperature gage (Radio Shack or Harbour Freight) and measure the upper and lower radiator hoses. If the supply hose to engine is significantly colder than the return then the coolant is staying in the radiator too long. I'll measure mine tonight and report back what the temps are for comparison.
3) Head gasket
Run engine with the radiator cap removed and smell the radiator fluid. If it has an exhaust smell then there is exhaust gas entering the cooling system. Check for air bubbles as well.
4) Cracked block
Same as #3
5) Timing - see below
6) Carburetor - I am going to go out on a limb - I would be very surprised if a carburetor could cause overheating at idle. The engine load is almost nothing and I would expect the cooling system to have plenty of reserve capacity to overcome any gross lean (or rich) condition - plus his plugs didn't look bad.
7) Thermostat - I think you said you have run a 160. Have you ever run without a thermostat. Might be worthwhile as the flow should be greater as well.
I would say yes you need to determine where TDC is on the HB. If the HB has slipped then you need to re-mark it. If the HB is moving around this might be like hitting a moving target though - I am not familiar with how these things slip but it sounds like they remain stable after they slip?? As a starting point set the initial timing to 10-12 BTDC with the vacuum advance disconnected and hose plugged. The engine should idle all day long at 10 BTDC. I would also check you mechanical advance by revving the engine to 3000 and checking the timing (you will need an adjustable timing light - not sure if this is the type you bought). With the initial timing set to 10 the total (mechanical+initial) should be about 25-30 BTDC at 3000rpm which means the mechanical is contributing about 15-20. Now for test purposes the vacuum advance is not really necessary so I would leave it disconnected and plugged. This will eliminate one other "timing" variable. I have been fighting a pinging problem and have been playing with different advance springs (HEI distributor) so I have been running without the vacuum advance for most of the summer. No problems other than slightly less cruise throttle response and probably less fuel mileage.
To answer one of your previous questions the vacuum advance can be connected to either manifold vacuum or ported vacuum. Manifold vacuum will give full advance at idle then will drop off and come back up as the engine is revved. The ported vacuum will be zero at idle then will gradually increase as the engine is revved. I don't think one is significantly better than the other although I tend to prefer ported FWIW.
Anyway, give theses things some thought and report back any findings.
1970 Cutlass Convertible, 455ci, TH400
........ Read here.
I once knew a Guy who had the same sort of heating problems, with his 455 powered '50 Olds 88 Coupe, for several years. He "trailered" it to the strips (low elevens) and drove it very little on the street, because of the high temps.
He replaced the radiator with a thicker and larger version (about ⅓ larger) aluminum version, added an inline electric pump, two electric fans, a custom made stainless steel shroud, and Water Wetter was his choice for coolant.
He asked me, on several occasions, how I could drive mine to Carlsbad, Bakersfield, or Phoenix, make a few passes, and drive it home, without any problems. I could only ask him, why he couldn't do the same.
I eventually bought his Red Coupe at a very good (his wife gave him the ultimatum) price. Put his 468, in place of my 437, drove it down to Carlsbad, made a few passes, and drove it home.
It has a stock '50 Olds radiator, with a 50/50 mix of tap water and whatever coolant was on sale at Autozone, a flex fan, no shroud, a 180°stat, and it ran at 180° (or so) Highway and City.
Norm
Too long = restriction = lack of flow = overheating.
And he also said, it was working properly.
Poor substitute for an optimal initial setting.
Right where it should be.
Not even close.
As soon as the throttle is opened, both ports draw vacuum from the same intake manifold.
Norm
Last edited by 88 coupe; Jul 29, 2008 at 11:59 PM. Reason: Corrected author name in quote #2
Norm you should explain what the fix is if you can. You can certainly pick apart nearly any thread where stupidity is dicovered, but what is the fix? I don't know either but I bet I could figure it out if were there. Are you with me on this?
Not possible, with the information we have been given.
Nothing to do with "picking apart" threads or "stupidity". If you wish to discuss my posting style, send me a PM.
In person (and before he started "fixing" it) an accurate diagnosis should have taken less than 10 minutes.
I have no idea where you are, or what you are on.
If you wish to discuss it further, send me a PM. You can start by telling me WTF you are talking about.
Norm
In person (and before he started "fixing" it) an accurate diagnosis should have taken less than 10 minutes.
I have no idea where you are, or what you are on.
If you wish to discuss it further, send me a PM. You can start by telling me WTF you are talking about.
Norm
Norm, you bring nothing positive to any post. If you don't know the answer stay out of it instead of critiquing everyone elses posts. I wish I were a moderator your *** would be off. Oh, forget all that I see you're from Socal. That explains alot.
Seems the simple checks may be the first thing to do -replace the t/stat ($4 ? )
reverse Flush the radiator
All very well to go down the track with the process but seems to me B follows A in most scenarios
reverse Flush the radiator
All very well to go down the track with the process but seems to me B follows A in most scenarios
O.K. Norm I'll engage. Not sure you understood some of my suggestions so I will try to clarify............
What kind of logic is that? It overheats on the highway so the airflow is not a problem? Enlighten me please?
You quoted gibbo69olds when it was actually I who said that - probably an honest mistake - just wanted to point it out.
What is the return coolant temperature - he needs to measure that to confirm the T/S is indeed opening at 160* or 180* or whatever he thinks is in there. Running without a thermostat should increase the flow. I say "should" because he could have restricted flow or crappy water pump or something along those lines. I was just suggesting another data point to try to narrow down a flown problem.
I agree. However, if you do some searching on this site and other Oldsmobile sites you will find many who swear by manifold vacuum for the advance.
I disagree. Ported vacuum will vary depending on the throttle plate opening. Ported vacuum will not be the same as manifold vacuum as soon as the throttle is opened. With small throttle openings ported will remain closer to zero than manifold.
I would like that. As soon as I get some more data I'll start one.
Quote:
Originally Posted by a911sc
........ I think you said you have run a 160 ........
And he also said, it was working properly.
Quote:
Originally Posted by a911sc
........ Have you ever run without a thermostat. Might be worthwhile as the flow should be greater as well ........
And that would prove what?
Originally Posted by a911sc
........ I think you said you have run a 160 ........
And he also said, it was working properly.
Quote:
Originally Posted by a911sc
........ Have you ever run without a thermostat. Might be worthwhile as the flow should be greater as well ........
And that would prove what?
Quote:
Originally Posted by a911sc
........ vacuum advance can be connected to either manifold vacuum or ported vacuum ........
There is no reason logical reason to use direct manifold vacuum.
Quote:
Originally Posted by a911sc
........ Manifold vacuum will give full advance at idle ........
Poor substitute for an optimal initial setting.
Quote:
Originally Posted by a911sc
........ then will drop off and come back up as the engine is revved ........
Exactly the opposite of what is needed.
Quote:
Originally Posted by a911sc
........ ported vacuum will be zero at idle ........
Right where it should be.
Originally Posted by a911sc
........ vacuum advance can be connected to either manifold vacuum or ported vacuum ........
There is no reason logical reason to use direct manifold vacuum.
Quote:
Originally Posted by a911sc
........ Manifold vacuum will give full advance at idle ........
Poor substitute for an optimal initial setting.
Quote:
Originally Posted by a911sc
........ then will drop off and come back up as the engine is revved ........
Exactly the opposite of what is needed.
Quote:
Originally Posted by a911sc
........ ported vacuum will be zero at idle ........
Right where it should be.
Quote:
Originally Posted by a911sc
........ then will gradually increase as the engine is revved ........
Not even close.
As soon as the throttle is opened, both ports draw vacuum from the same intake manifold.
Quote:
Originally Posted by a911sc
........ I don't think one is significantly better than the other ........
Not even close.
Originally Posted by a911sc
........ then will gradually increase as the engine is revved ........
Not even close.
As soon as the throttle is opened, both ports draw vacuum from the same intake manifold.
Quote:
Originally Posted by a911sc
........ I don't think one is significantly better than the other ........
Not even close.
I would like that. As soon as I get some more data I'll start one.
I'm sure everyone else will appreciate it, as much as I do.
The same logic I grew up with.
Do you want to stay on topic, or are you trying to start another pizzing contest?
Isn't "enlightenment" why we are here?
Thanks for the clarification. I'm sure everyone else appreciates it, as much as I do.
Having said that: If I edited it, to reflect the correct author, would it make my statement any less valid?
"Common Courtesy". No need to explain it.
Assuming you are serious: Not the way it works. Protocol is, that since you made the statement, you do your own search, then post any relevant links.
No doubt
I would expect that they all based their opinions on the subject post, at the following link.
https://classicoldsmobile.com/forums...html#post39036
Norm
The same logic I grew up with.
Do you want to stay on topic, or are you trying to start another pizzing contest?
Isn't "enlightenment" why we are here?
Thanks for the clarification. I'm sure everyone else appreciates it, as much as I do.
Having said that: If I edited it, to reflect the correct author, would it make my statement any less valid?
"Common Courtesy". No need to explain it.
I would expect that they all based their opinions on the subject post, at the following link.
https://classicoldsmobile.com/forums...html#post39036
Norm
Is there any way to actually test how coolant is flowing through the engine to try to find blockages without having to tear the engine apart? Is it possible the thermostat is staying open at all times and not giving the coolant a chance to absorb heat from the engine? Have you measured the inlet and outlet temps at the radiator? Im not sure if any of these will help, just throwin out some suggestions.
Radiator flow can be checked by running the engine, with the cap removed, and looking into the opening. Whether the coolant is moving, or not, will be obvious. Judging whether the flow is adequate, is best left to someone with some experience, in that area.
My advice, in post #67 applies.
If both hoses are the same temp, there is a flow (air or liquid) problem. If the lower hose is substantially cooler, there is no problem.
Your thoughtful questions are a welcome change.
Norm
It would be wise to listen to Norm, however painfull the answer may be. Do not let your ego be attacked, just your thought process. Stubborness is NOT a good thing.
Electric water pump?
Any corrosion in the Aluminum radiator? How many miles on it?
HAVE IT CHECKED.
JMO JIM
Electric water pump?
Any corrosion in the Aluminum radiator? How many miles on it?
HAVE IT CHECKED.
JMO JIM
It would be wise to listen to Norm, however painfull the answer may be. Do not let your ego be attacked, just your thought process. Stubborness is NOT a good thing.
Electric water pump?
Any corrosion in the Aluminum radiator? How many miles on it?
HAVE IT CHECKED.
JMO JIM
Electric water pump?
Any corrosion in the Aluminum radiator? How many miles on it?
HAVE IT CHECKED.
JMO JIM
OK guys so I finally have some time to work on this, actually only three nights. Leaving for vacation on Saturday morning at midnight. I have not done much with the car except start it up every now and then. I did play around with the timing last night. First question, is it odd that none of the vacumm ports would be the ported vacumm? I put a gauge on all ports on the carb and manifold and they are all pulling a vacumm at idle.
Next I want to take a vote, all are welcome,
What do you think the issue is? Please give ONE possible contributing factor and how you would check it out. I am trying to not overload myself and have a clear objective.
I will also be focusing on this once I return from Vaca. I would like to drive the car for a couple weeks before the season is over.
Thanks again guys,
Steve
Too many projects and not enough time. I think I need to sell a couple toys.
Next I want to take a vote, all are welcome,
What do you think the issue is? Please give ONE possible contributing factor and how you would check it out. I am trying to not overload myself and have a clear objective.
I will also be focusing on this once I return from Vaca. I would like to drive the car for a couple weeks before the season is over.
Thanks again guys,
Steve
Too many projects and not enough time. I think I need to sell a couple toys.
I had this problem on an old 371 Olds..It turned out to be a microscopic crack in the cylinder head that was letting exhaust gasses into one of the cooling passages.. Simple test for this? I let the car warm up without the radiator cap on and you could see bubbles of air rising to the top of the radiator.. Maybe not the smartest thing to do but it worked for me. This didnt happen until the car was warmed up for about 20 minutes
59-59-59, How did you determine which head? Did you replace both? Could it not have been anything else that would cause these bubbles? I do have an extra set of heads but do not want to do a lot of extra work till I find it.
Bubbles
OK, I do see bubbles. I want to make sure that there is no other reason I would see bubbles than a crack in the head. Also my coolant level does not stay at one level. I have to add mixture after many starts and only running for probbaly 20 - 60 min each.
Read the following, again:
They remove the radiator cap, only.
At the end of that "few minutes" they can tell you the actual cause of your problem and the cost of the repair.
Norm
At the end of that "few minutes" they can tell you the actual cause of your problem and the cost of the repair.
Norm
Beats the hell out of me! Since I was dealing with about 50+ year engine, I sent BOTH heads to the machine shop to be magnafluxed. The crack was found and the crack repair was made and both heads were shaved down. Replacing heads was out of the question, since the last time anybody made 371 heads was quite a while ago.
Well I am not 100% sure that the car is fixed as it always seems to pop back up but it appears to be air flow across the radiator. I can confirm once I get through the whole summer without problems. I started out basic and pointed fans on the rad. Although I think the timing is still off (to be looked at next) the car ran cool. I also talk to local guys and found a trick that pointed to the same thing. I didn't want to invest in a different elec fan setup so I pulled the elec water pump off and ran the mechanical with a flex fan and have driven it multiple times now with no problem and can idle in the driveway. It is odd though at highway speeds the car would still overheat thats why I still have some doubt but I will keep everyone posted and thank you all for your constructive help.
I have to say that I've never had an overheating problem with BBO in any state of tune. There's clearly something wrong. It could be blockage in the cooling jacket, it could be a very small head gasket leak, whatever, but your combo should not do this even when sitting in the driveway.
I also caution everyone that the number of rows in a radiator is not an important metric. It's the total surface area of the tubes that matters. Many aftermarket aluminum radiators use tubes up to an inch wide. My 86 with 307 has a single row aluminum radiator and it runs cooler than the OEM three row copper unit. Most big block aluminum radiators use two rows of the wide tubes and they cool just fine. The issue with either corrosion in the radiator or crud that's worked loose from the block and is plugging the radiator is a good point and should be checked.
I also caution everyone that the number of rows in a radiator is not an important metric. It's the total surface area of the tubes that matters. Many aftermarket aluminum radiators use tubes up to an inch wide. My 86 with 307 has a single row aluminum radiator and it runs cooler than the OEM three row copper unit. Most big block aluminum radiators use two rows of the wide tubes and they cool just fine. The issue with either corrosion in the radiator or crud that's worked loose from the block and is plugging the radiator is a good point and should be checked.
And a correct shroud is essential. Aftermarket fans that suck air through just *part* of the radiator don't help either.
From post #12:
Not enough advance can cause overheating. Too much advance can only break things.
Norm
Norm
overheating
Wait a minute guys, it's the overheating he's worried about. I've been racing since 1970 and carbs, vacuum advance,wires, tailpipes, batteries , aren't really gonna cause his problem. He needs to just go out and buy a good 31x19 aluminum radiator and throw in a 160 degree stat and go down the road and forget about it. Thank-you
My 455 runs consistently @ 200 degrees does that sound right? I
think the thermosat opens up around a little over 200. Does that sound correct I don't wanna heat it up
think the thermosat opens up around a little over 200. Does that sound correct I don't wanna heat it up
They keep engine temp regulated by their action.
It sounds correct, but I would use a 180 t-stat, myself.
Jim



