Sarum

My '65 Cutlass (330)has suddenly started overheating in a major way and I haven't been able to figure out why as yet.Neither has the mechanic! I hope you guys can point me in the right direction.The Derales fan/controller cannot stop the engine from overheating despite it coming on early at the moment.
As background please see the following:
I pulled the thermostat out and did the boiling water/not boiling water test 3 times and the thermostat opened and closed just fine. While I had the thermostat out I filled the engine with water at the thermostat housing location and had my wife wind the engine over. I was rewarded with water pumping out of the thermostat hole in the intake manifold.
The car has a nice Griffen alloy radiator and is fitted with an Edelbrock Performer RPM intake. As I now believed the thermostat and the water pump were functioning properly and everything else looked minty I was fresh out of ideas I got my local mechanic to have a look.Despite me telling him what testing I had done the mechanic maintained it was the thermostat that was causing the overheating.After replacing the thermostat there was no change as the car still overheated quickly, even sitting idling.
When I rang him again he then told me that he had pulled a hose off the water pump and no water came out so the water pump was faulty and would have to be replaced.During the phone conversation he agreed with me that the hose he had disconnected was the heater return. As this didn't sound right to me I went and picked up the car and have just done another test myself.
I disconnected the small bypass hose that is fitted to the thermostat housing underneath the top hose/intake manifold connection.The other end of this short hose connects to the water pump. With a finger in each of the 2 holes the engine was started and coolant started squirting out of the thermostat housing bypass pipe fitting.This suggested that the pump was working to some degree at least.I have just done a bit of research and have read that the pump discharges coolant into the front engine cover and from there coolant pumps into both banks of the engine.Next coolant pumps into the full length water jackets on each side of the block and up into the cylinder heads.After flowing through the cylinder heads coolant exits at the front of each head into the water passage in the intake manifold, and then through the water outlet into the radiator.
When the thermostat is closed all of the coolant flows through the bypass down to the water pump inlet and back into the engine block.
So having coolant squirting out of the bypass fitting on the thermostat implies that the pump is working so what on earth is causing the overheating?

oldcutlass

What temperature is the engine reaching at idle and cruise?

AZ520

That sounds like impeller slipping or lower hose collapsing. You might get some water shooting out while cranking but when the system is sealed and building pressure the impeller or even belts may be slipping. I would leave t-stat out and check water flow through radiator with the cap removed. If you see good flow that increases with rpm thats good, then put the cap on and see what happens, feeling upper and lower hoses with your hand. You could see the lower hose collapse or feel for temp at both hose to verify circulation. I like to run the lower hose with inner spring always as a precaution. If this checks out you might have a head gasket issue.

Fun71

So something has recently changed. Has the weather got warmer recently? Perhaps the issue has been masked by cooler ambient temperatures?

I am not a fan (no pun) of electric fans - they seem to be involved in a lot of discussions about overheating issues. Perhaps post some images of your setup so folks can get an idea of what you have.

BILL DEMMER

my original 330 did that suddenly too, causing violent boiling and expulsion of coolant from the overflow tube. mine lost a head gasket, i hope yours didn't.

bill

FStanley

although odd I had a water pump empeller loose its press fit on the shaft. sometimes the rebuilds are not good,. maybe even new??


I found the problem by taking off the fan belts, and bypass hose, I then ran a stiff wire down the bypass on the water pump. I found nothing happened, no resistance.

I then took off the water pump and the empeller fell off in my hand..

also look the thread below lots of good info/discussion on cooling

https://classicoldsmobile.com/forums...take-heat.html

Sarum

At idle I have been shutting the engine down at 250 degrees F but the gauge keeps climbing from there. At 60 mph cruise with the fan on it seems to hold at 200 degrees but as soon as I slow down back into 30 mph zone the gauge climbs rapidly.Normally just getting to highway speed is enough to reduce the temperature to an acceptable range i.e no fan needed.BTW the fan controllers probe is mounted into the radiator.Thanks

oldcutlass

Did the system hold temp before? As Kenneth asked did this just start happening? Are you losing fluid?

Sarum

Hi Bill,
Fortunately I keep an almost constant eye on the temperature gauge and have not had any boil over stuff happening. Attached via rubber pipe to the radiator is an alloy tank which also has its own overflow tube.The radiator does not have a pressure cap but the secondary tank does.I guess that means that it would take quite a lot before I would see coolant coming out of the tanks overflow pipe.

Sarum

I think the hoses are OK,they both get highly pressurised and very hot when the engine is running for any length of time.When I did the test I had one finger in the heater return port on the pump and one in the thermostat bypass port on the thermostat cover. When the engine was RUNNING I noted that I had good coolant pressure at the thermostat cover port but nothing at the pump.Having good pressure at the thermostat bypass port on the intake manifold side is as it should be with the engine running.
I am just off to the shed to see if I can see any coolant flow in the radiator with the cap off as you suggested.

Sarum

Good thinking. We are at the end of Spring - start of Summer and the weather has been nice the last week or two we are probably talking a peak difference of 6 degrees C and the car only gets used in nice weather normally. I have also been driving to town the long way around because of the roadworks guys using lime on the road surface.So it is possible that the fault has been there a wee while I guess.

Sarum

Thanks for the info and the link.

Sarum

[QUOTE=AZ520;1057957]That sounds like impeller slipping or lower hose collapsing. You might get some water shooting out while cranking but when the system is sealed and building pressure the impeller or even belts may be slipping./QUOTE]
Just did as you suggested i.e looking into the radiator with the engine running.
Each time I topped the coolant up it was sucked away as soon as I raised the engine rpm - had to fill it up half a dozen times. I could definitely see coolant squirting out of 2 horizontal ports at the top of the radiator and that as well as the fact that coolant kept getting sucked away when the engine revs were increased makes me think the pump is operating.
However on the way back from the shed something dawned on me thanks to you. The water pump does not have its own belt from the crank and couldn't have with my car at least as there is no tension adjustment for it to use,
To operate it relies totally on contact with the power steering pulley belt as it goes past and the same thing with the alternator pulley belt.So for the pump to work properly the tension on those 2 belts has to be spot on to drive the pump pulley.Back to the shed!

AZ520

Oh wow sounds low on coolant, or air pocket, you will get it soon

classicmuscle442

Pressure cap should be on radiator not overflow tank, also sounds like it was low on coolant by your later post. When radiator cools it will suck water back into it from overflow tank. Car did not have a overflow tank on it from factory, fill level is marked on side of upper radiator tank if original, coolant level should just cover top tubes when looking in radiator.

TRWham

These are classic symptoms of a fan problem. The fan alone is not providing sufficient airflow for cooling. It could be the fan is too small, not correctly shrouded or not running fast enough or in the right direction.

I would check the fan sizing and installation, and verify the wiring is correct (high speed/ low speed, etc.). It may only be running at low speed. Make sure the wiring is big enough too. These things draw big current.

rustyroger

You say you have an electric fan fitted. What other modifications?, particularly shroud removal or anything affecting air flow through the radiator. If it gets too hot cruising at 60mph without the fan on then you have either something affecting coolant flow, plugged radiator or it is too small, bad water pump, collapsing hoses, or a bad thermostat. Or air isn't flowing through the radiator in sufficient quantity. You should never need fan assistance at highway speeds, or any speed much over walking pace come to that.
Another possibility is a bad head gasket, or in a worst case scenario could be a cracked head.

Roger.

oldcutlass

If it's holding temp fine at cruise speeds, and not at idle then you have a fan/airflow issue.

Sarum

I have always made sure that the radiator is topped up and have only lost fluid when disconnecting pipes while trying to sort the problem.
The current setup is pretty much how I bought the car some years ago and has worked fine until now.The car has a large Griffin alloy radiator with a 12" Derales fan and fan controller..The only change I have made there is changing from a plastic overflow tank to an alloy one.Having a pressure cap on the overflow tank seems a bit weird I admit but I would have thought the net result is the same.

Sarum

Hi Eric, yes the cooling system has worked well up until now and the issue has just started recently.I am not losing any coolant apart from that I lose taking hoses off etc.
The issue has only started occurring during the nice weather we have been having and I have been driving a little further than usual due to roadworks.
Maybe the extra engine running time and the additional distance allows the overheating to occur.

Sarum

I should have thought of this much earlier (so should have my mechanic) but last night I checked the belts that drive the water pump and found the power steering could do with tightening.After adjusting/checking the power steering and alternator drive belts I took the car for another test drive.I made a couple of stops on the drive as well as driving both in a low speed area and highway and the system appeared to be working normally again. I could watch the fan come on at 185 degrees and then watch the temperature drop away until it reached the normal range.
Sadly as I was getting close to home and coming off a 100kph to a 80kph area the temp kept climbing uncontrollably and the engine was detonating badly when I gently pressing the gas pedal.The temp got to 230 degrees fast so I ended up sitting on the side of the road, hood up waiting for it to cool down.

Sarum

After getting the car home and cooled off I decided to have another look at the ignition timing as I believed the current timing may be a little advanced.In January 2017 I had to replace the HEI distributor and also fitted a Pertronix Flamethrower ignition module. I never got everything 100% as my flash new digital timing light stopped working and I had to send it to Australia to be checked out.
Test results from last night are as follows. BTW I took the car for a short run to warm it up for testing and there were no problems.

40 degrees @ 820 rpm idle Vacuum port hose still attached to distributor
Intial Timing 20 degrees @ 670 rpm idle Vacuum hose disconnected and
plugged

Results below were taken from where the cursor stopped moving back to the TDC mark.
Mechanical Timing
1st test 36 degrees @ 1900 rpm
2nd test 40 degrees @ 2140 rpm
3rd test 32 degrees @ 1610 rpm
The distributor came with an adjustable vacuum facility which I can use to stop the pinking at cruise at least.
.Normally I would hear one ping as I pressed down on the gas pedal from a cruise situation.Since the car started overheating there has been slightly more pinking but going back to the last overheating (while test drivng after adjusting the drive belts) the pinking was a lot worse prior to me pulling over and shutting the engine down. Temperature went up to 230 degrees on the gauge.
Can someone please tell me if the ignition timing needs retarding mechanically?
If bad timing isn't the cause of the overheating that really only leaves the waterpump. I suppose it is possible for the waterpump to look OK (no leaks) and sound OK but still not be working properly even not working intermittently.

Fun71

My experience is water pumps either work or they don't. It is a simple system with an impeller on a shaft that is driven by the pulley. If you have water flowing, then the pump is functional.

AZ520

I have an hei dist. and find my engine runs coolest at 10 degrees base timing and runs best with the vacuum advance hooked up to manifold vacuum. You should retard your timing some and also make sure the damper hasn't slipped.

oldcutlass

Do you have an HEI or a stock distributor with a Pertronix points replacement? If an HEI, drop your initial timing to 16* without vacuum connected. If its a Pertronix points replacement, drop it down to 10*.

Is your temp climbing really fast, like in seconds. Or slowly over a long period of time?

FStanley

I was fooled by this as I was getting some flow at all rpms but not enough, I later found empeller lost its press fit and slipped. like I said earlier I found the issue running a wire down the bypass hose and turning water pump pulley by hand. drove me crazy finding this.. newly rebuilt too.. for rebuilt parts I NEVER use chain stores anymore , I go to the rebuilders directly even if I pay more...


Sarum, if you were running OK temp wise before, it seems to me something let go to cause the overheating now some type of failure..

FStanley

Sarum,

Curious, why do you think your timing is an issue just now?, ASSUMING it cooled OK before.

mmm I think you need to prove out cooling system is working OK before you put effort into timing issues. You need to try stuff to check it and tell us what you are seeing.

Autozone has a ton of cooling test equipment you can rent for FREE. Things like exhaust gas in coolant, will the system hold pressure, is the cap good, etc etc. Do the basics first, otherwise you just drive yourself crazy..


For the timing, I don't think you mentioned the cam or specs, compression ratio, etc to advise properly on what your timing should be. Also there are a ton of other messages already posted in this forum

oldcutlass

I asked the question because the Pertronix HEI is called a Flame Thrower, so I am a bit confused of his description. He also lives in New Zealand, so the Autozone suggestion is n/a.
http://www.jegs.com/p/Pertronix/Pert...49237/10002/-1

Sarum

The car has a new (in January) "billet" HEI dsitributor from Summit, MSD button,and Pertronix Flamethrower module that has inbuilt rev limiter and a few other trick things.
I changed the initial timing down to 16 degrees as suggested but I did notice the engine RPM dropped off and idling became rougher. Also it seemed to have lost power when driven so I will most likely change it back up a bit.
Funny thing is to reduce the degrees showing on the timing light I had to move the distributor in a anticlockwise direction.As an Olds distributor moves anticlockwise I thought to retard timing I would be moving the dsitributor clockwise.
I now also have the adjustable vacuum advance fully anticlockwise as the distributor installationinstructions advise.If you experience any detonation at cruise/under load you then start altering the vacuum with an Allen key.
Incidentally I looked in the Factory Service maniual and it advises 7.5 degrees initial timing at 850rpm for all Old's V8 engines.
I guess they could use that setting because of the better quality fuel they had back then.

I just took the car for a test drive with the altered timing but things didn't go so well. As the engine was already warm(fan had come on) from me working on it at idle I decided to switch the fan on manually for my trip into town.After a few minutes the gauge started climbing and when it got to 200 degrees I turned around and went home as the cooling system obviously wasn't able to cope.
As the fan itself seems to be working normally that really only leaves the water pump itself. Even though I know the pump works at low rpm the impeller must slow down or stop completely at higher engine speeds.
The only bad thing I have had happen previously was with a 1974 Holden Torana SLR5000 V8 manual that grenaded a couple of water pumps under hard acceleration in 2nd gear. Very embarrassing looking in the rear view mirror and seeing bits of metal, belts and the fan bouncing along on the highway behind me.

I will check out the other posts I have not got to yet but it looks like my next step is to remove the pump.Thank goodness, apparently there is a company an hours drive away that can recondition water pumps so I won't have to import a replacement from the US.

Sarum

Were you expecting to feel the impeller or shaft rubbing against the wire because the engine was running? No, that can't be right as you took off the drive belts.Why did you remove the belts? Please explain.

Sarum

As per previous the coolant level has always been correct.I had considered an air pocket because the top hose is higher than the radiator.Yeah, I know it's not the best but it has never been a problem previously.The hoses both get very hot and under high pressure so I discounted the air pocket idea.
However, if there was an air pocket somewhere else would not the pump's pressure move that air bubble along to the top of the radiator and then be expelled out of the overflow?
If the air pocket was not expelled how would I prove there was one?

steverw

Has the engine ever been rebuilt? If the answer is no, its possible that alot of the space in the cooling jackets of the cylinders have alot of crud built up in them, allowing less coolant circulating around the cylinders. After having my motor vatted during machine work, i still scrapped out almost 1 pound of crud from deep within the water passages around the cylinders. That crud takes up space where coolant would normally flow.
Just a possibility, something to look into.
Steve

Fun71

If you plan to do something that extreme, first simply remove the thermostat, disconnect the upper hose, and see if the pump pushes water out. It should move a LOT of water in a short amount of time.

76olds

I would move the cap back to the radiator and put the original fan back in place of the electric one/s myself. Are the fans set up as puller or pusher ? how long have you been running the current setup prior to overheating?

AZ520

I like to drill a 5mm hole in the t-stat to help ensure I don't develop an air pocket, also raise the nose of the car and open the heater valve fully with the engine hot and running to ensure no air trapped. Have you ran it with the t-stat fully removed yet ?

olds 307 and 403

Put the timing back where it was. Try removing the thermostat and running it. It sounds like your fans are weak, what brand are they? Most aftermarket fans are not up to task.

FStanley

OK let me clarify what I missed..

1. First I took off all the fan belts

2. I drained the radiator so I didn't have coolant all over the place.

3. I took off the bypass hose at the water pump

4. I ran a stiff wire down the water pump bypass fitting hole

5. I turned the water pump pulley by hand, back and forth, I had no resistance

6. I said Phoey and took off the nice correctly painted water pump off the engine which I didn't want to do.

7. After I took out the water pump, the empeller fell off the shaft, so much for a "press fit"

this was for an engine that was just fired up for first time, I thought I did something wrong, really ^(#@%@()!_ me off went to hot immediately, I shut down at least 10 times before I figured it out..

oldcutlass

Although the impeller issue is usually very remote, glad you found it.

classicmuscle442

Did you get it fixed? Still cannot understand adding overflow tank with radiator cap on it. Olds built a lot of cars and they did not have overflow tanks on these earlier ones, including big blocks 400's.

Cutlass Fan

Who ever installed that over flow tank didn't understand how an over flow tank actually works.