Who has heard the thin-walled cylinder 455 engine is prone to overheating.

I was just told by a very knowledgeable Buick person, because Buick engines have thin-walled cylinders it's prone to overheating, especially if it's been bored.

Is that true?
Reason why I ask, I have been going through a lot of overheating issues on my 455 engine.

Everything has been investigated, checked and several parts replaced.

(1) Several fans clutches have been replaced with another one on the way.
All fans clutches have been HD Thermostatic models.
(2) Replaced radiator with another HD four core model.
(3) Car has been tuned to factory specs, so timing is not an issue.
(4) MSD ignition system is installed.
(5) Checked to make sure the temperature sensor was hooked up correctly and it is.
(6) Engine compression, outstanding. Average 180 psi.
(7) Leak down test was outstanding.
(8) Gasoline, 93 Octane runs great.

I have my car in a Classic car shop.
Temperatures while cruising at highway speeds (60-70 mph) with AC on,
200-210 degrees.
Stopped and idled, temperature hit 220 degrees in less than two minutes.

This has happened with two different thermostatic HD fan clutches.
One HD clutch, Delco model made a huge roaring noise, had to remove this unit. Thought it might be locking up most of the time.

Every part on the Buick is original for this engine.
Crank pulley.
Water pump pulley.
High volume water pump
7 Blade fan blade.
Fan blade, 18-inch diameter.

I have read everything I can get my hands on and the shop has checked every possible problem.
Because the new radiator made no improvements and the 2 fan clutches, we tried, one being from the Parts Place didn't work but the Delco HD model did cool the water temperatures to specifications (180* when cruising & 190*-200* during idle and in stop & go traffic) but was very loud and roaring so much I couldn't stand the noise.

We have decided to try another HD fan clutch, a Four Seasons model in search of lower water temperatures. I hope this works....
Any suggestions ideas to solve this problem? Vet (Navy)

 

Several pieces of information you didn't mention. 1) How much was the block bored? 2) What thermostat is installed now? 3) You mentioned timing to factory specs. How much static advance is set and how much total advance. Finally 4) Are you using vacuum advance and how much?

 

I had almost an identical problem and tried all the same solutions and still was having temps on my quality 2 1/8 Stewart-Warner gauges of 198-215 f. In 90 F. Weather. I put my laser temp Gun on the upper radiator hose and radiator, and even the thermostat housing and it always read 10-15 degrees cooler than the guage…….I stopped worrying about it.

 

Bored .030, that's not much.
160 degree thermostat.
10 degrees initial advance.
32 total advance.
I didn't set the vacuum advance but we purchased an adjustable vacuum advance unit. I didn't ask the mechanic what he set it at.
After I purchased the Buick, that's when I found out I had dedonation issues. Main reason we went with the MSD system and adjustable vacuum advance system.

It's been in the shop for awhile and when the Delco HD fan clutch was installed, the car performed really good. No bog, instance performance.
Lays rubber, no problem, even with a highway geared 2.93 differential.

Like I said, the Delco HD fan clutch worked great to keep the water temp at the correct operating temp, but the roaring noise is more than I can take.
I'am hoping the incoming fan clutch will cure the problem.

 

Buy one of these ====https://hambydairysupply.com/floating-dairy-thermometer/

Remove the Thermostat ( hopefully it a after market mechanical )

Now take it in the kitchen and see if they both have the same temp reading...

 

That's interesting to know. I just bought a laser temp gun.
Never thought to check the areas you did.

Can't wait to replicate what you did.
Strange thing is, the car never over heated on me. I changed the dash gages fron analog to digital. So originally I couldn't really tell what degrees the water temp was at.

I will give the laser gun a try and see what kind of temp readings I get.

 

That's an interesting try. You just reminded me of something I overlooked. I told the shop to replace the original thermostat with a new 160 degree model.
I wanted everything to be new when the new radiator was installed.
The original thermostat was also a 160 degree model.

 

Vacuum advance can have considerable effect in heat due to timing event during idle and cruise.

With vacuum advance initial and total mechanical are almost non-existent at idle and cruise where timing has effect on temps.


So, figure out where your engine is operating and what timing is occurring at idle and cruise.

If you have properly working stat, shroud, clutch fan and the car is good at cruise, and you are seeing temps of 220-220F at idle above 90F ambient air temperature, and you're running A/C, and temps drop below 200F when you start driving away from a traffic light, you are not hurting anything.

If you start seeing temps going above 220F at idle, and never dropping when you start moving, then you need to begin sweating , and looking for a problem.

Otherwise, you are gonna work yourself into a sweat, and never enjoy your car...



Thermostats only deal with the minimum temp of coolant, and have nothing to do with the max temp.

Max temp is controlled by radiator efficiency, assisted by a proper shroud and fan fit, and a fan's ability to move air.

Second to that is proper amount of coolant, flow(pulley size and pump properly working).

It is a system of many components and variables.

You chase one thing or leave out others, you just die hit and tired in the side of the road.

 

In a word... NO

This notion that thin wall castings promote overheating is an old wives tale. As with many of these tall tales, there is a kernel of truth. That being, a thinwall casting promotes faster heat transfer to the coolant.. the inability of the cooling system to remove that heat is the issue here. As Mike said above...

Let me give you an example of how this comes about:

So guy "A" rebuilds the motor on his GS, that has a marginal cooling system to begin with. It's bored and honed oversize to get back it's ability to seal the cylinders.. He ports the heads, installs a bigger cam, all of which introduce more air/fuel into those now tightly sealed cylinders, the result of which is more heat produced. But now his marginal cooling system is completely unfit for the task at hand, and the result is higher coolant temps on his gauges.

Now, there certainly couldn't be something wrong with his pride and joy, so it must be that darn Buick thin walled block causing the issue.

"Ya, I don't think so Tim"... ( quote from Al in the 90's TV show "Home Improvement")

Now, another thing that bolsters this notion, is caused by guys going thru what your dealing with here.. no matter what they do, they just can't seem to eliminate this issue. You get to the point that you would pee on a spark plug if you thought it would help.. been there, trust me.

Here's some random thoughts:

One thing that is often overlooked, is a block that has a ton of corrosion in the water jackets. I have seen core motors that we have taken apart, and witnessed the slot in the rear of the block, where the majority of the coolant is going to pass thru, be restricted by as much as half.. from corrosion and sediment.

Usually not a problem on a rebuilt engine that was cleaned properly.

On thermostatic clutch fans.. they activate based on heat radiated from the radiator.. and if your radiator is not putting off the heat, the fan clutch will not activate..

You say that you replaced your radiator with "another HD 4 core unit".. so was this new? If so, what brand? I have seen more than 1 new HD radiator not be worth the box it comes in..

I would recommend an aluminum HD 2 core unit, get some recommendations from guys on the board here who have done just that. This should help keep your cruising temps in the 180-200 range where they should be.

You said "HD water pump"... whose specifically?

What your experiencing is known as "temperature creep".. at low engine speed.. caused often by a combination of things:

* Inefficient radiator that does not put enough heat across the bi-metallic spring of the fan clutch at during low airflow situations, to activate the fan. You can replace fan clutches till your blue in the face, but the problem is actually the radiator. Most electric fan setups are designed for high efficiency alumium radiators.. and don't work anywhere near as well as a good clutch fan/shroud combo, especially on older radiators.

The test for the fan clutch is simple... when your at 220 at idle, that fan should be locked it, and sound like a jet engine under the hood... hard to miss. Those 7 blade fans throw off a tremendous amount of air when the clutch is locked in.

* Not enough coolant flow.. water pumps, just like oil pumps, are speed dependent on their ability to pump. So just as your oil pressure drops when the engine slows down, from the reduction of volume out of the pump, so does the amount of coolant flowing thru the system. TA has the only water pump on the market which actually has bigger passages in the pump, to flow more water at low engine speeds. This had proven to often eliminate the "temp creep" situation in many of our GS's, but remember, it all comes back to the radiators ability to shed heat.

Personally, I have no use for thermostats in a summer driven car, they do nothing but restrict coolant flow, which is not needed by this engine. The design of the water jackets are restrictive enough, as noted by comparisons of coolant pressure readings on the dyno, compared to other domestic V-8 engines. Our 455 requires about twice the water pressure to push the water thru it. So taking the thermostat and installing it on the bench where it belongs this time of year will not hurt the cooling systems efficiency.

JW

 

Do u have a fan shroud????? I didn't see that mentioned or not in all your stuff

 

Yes I do and it's made for the 18 inch diameter 7 blade fan.

I forgot to include that in my information.
I also checked to see if the fan was 1/3 inside the shroud and 2/3's out as recommended.
I have checked and double checked almost everything on the cooling system.

 

Hi JW,

Am i reading you correctly to think that you would run no thermostat at all in South Florida where we are above 60 325 days a year and above 80 300 days a year.

hector

 

I tried removing the thermostat last winter. While the engine ran maybe 10 degrees cooler on 80+ degree days (170 vs 180) , it never got to a good operating temperature when it was below 50 deg. outside. So, I put the 160 thermostat back in. I'm in Central Florida BTW.

 

Any clutch fan that is working correctly sounds like a jet taking off when it comes on. You state that you had no issues with the temp with the HD clutch. Unfortunately that is just what it sounds like on a correctly working factory fan setup.

Mike

 

And there are high flow thermostats that much less restrictive... if you still want to/need to run one.

 

Really... That amazing because when I purchased the Buick, it didn't make that noise. I also never did know what type of clutch fan the car came with. I've been told that the original clutch fans are Centrifugal. Don't know if that's correct or not. I know the guy who does the Restoration is a Buick purest and does his best to do his Restorations to 1970 Buick specifications as close as possible. He wasn't happy when I changed some of this work.
I added buckets seats, floor console with floor shifter. He said I devalued the Buick GS, but I told him I will never sell or flip the car. He then said I guess it's ok then. I'm not into trying to make a profit. I'm 74 so, it's all about cruising and car shows and telling big lies about our cars. LOL

When the shop installed the roaring Delco thermostatic fan clutch and I complained about the roaring, they said that's normal.
I said, how come I didn't have that issue with my original fan clutch, they couldn't answer that.

I have to say, I've had several muscle cars (mostly Chevy SB's) and never had this issue. This IS my first Buick BB. This engine is all new to me.

So, it sounds like you think I should re-install the Delco fan clutch and put up with the roaring sound????

I must admit, I'm spending loads of $$$$ trying to cure this problem. I have to think about your suggestion. I might have to buy some ear plugs.
Vet (Navy)

 

The clutch on my yukon does the same thing when it locks in.........its coupled up and spinning at engine speed moving a maximum amount of air.......when it cools off enough it releases and quites down.

Using fluid like Evans coolant can also help reduce temps. Its not cheap but does cool better and have a much higher boiling point than normal coolant.

 

Yes, the experience on this board is second to none. You can copy and paste the suggestions into a Word document or just print them and organize them later. You can always "bookmark" the threads you like to revisit too.

Mr. Gasket / FlowKooler, etc
https://www.summitracing.com/search...y/engine-size/7-5l-455/engine-family/buick-v8