Overheating?

[hinoonaz]

Here goes my 2 cents. Hi volume water pump, drill two holes in thermostat and the fan shroud has a good seal with large cfm fan. I suffered through overheat issues for a long time. When the engine was rebuilt I had the shop drill and tapped holes in the intake manifold across the firewall end (used marine grade fittings and line) with a line going forward to water heater point. I have hit two hundred but was running high rpms for awhile. Immediately goes back to 180-185. In Arizona at 110 no problems. Stop and go non issue.

[DanEC]

A little different tack - your temperatures don't sound like anything to worry about based on your description so far. But, it may pay to check your timing and make sure it's where it needs to be and is not retarded. Also, if you have vacuum advance on your distributor (probably not) be sure it's hooked up to a manifold source of vacuum. You don't want ported vacuum advance - that's a 60's era pollution control device.

Insufficient timing advance is a major contributor to engine overheating - especially around town and at low speeds.

[snakesaway]

Originally Posted by DanEC

A little different tack - your temperatures don't sound like anything to worry about based on your description so far. But, it may pay to check your timing and make sure it's where it needs to be and is not retarded. Also, if you have vacuum advance on your distributor (probably not) be sure it's hooked up to a manifold source of vacuum. You don't want ported vacuum advance - that's a 60's era pollution control device.

Insufficient timing advance is a major contributor to engine overheating - especially around town and at low speeds.

I do need to check the timing just need to find the timing gun but that was something that has been suggested. On the vac advance front the dizzy does have vacuum advance and it is feed from the carby which is a holley. I recently replaced the tube for this as it was old and didn't fit tightly.

Thanks

[DanEC]

Originally Posted by snakesaway

I do need to check the timing just need to find the timing gun but that was something that has been suggested. On the vac advance front the dizzy does have vacuum advance and it is feed from the carby which is a holley. I recently replaced the tube for this as it was old and didn't fit tightly.

Thanks

OK - Holleys have different vacuum sources depending on the model. You want to hook it up to a vacuum source that comes from below the throttle blades and not above. Basically just make sure it's pulling a strong vacuum signal when idling by pulling the hose off the carb and making sure there is good suction.

A ported vacuum source is from above the throttle blade and has a low vacuum signal at idle but it will increase at steady throttle as the throttle is opened and airflow increases. OK for the highway but doesn't do much at idle or low speed.

I have an old Corvette and factory was ported vacuum advance - switching it to manifold vacuum outlet off the Holley dropped it's water temperature when running around town by probably 15 - 20 degrees. It was a startling difference. Good luck.

[*13*]

I read through the first page & see you have a couple more pages of suggestions so i'll just be short & sweet.

Make sure you check your timing. bring the #1 piston to TDC & see that the timing mark aligns on your balancer.

Location of your thermostat can make a difference. I have a remote, inline stat that opens in cooler water than is in the block.

Lastly. If your engine is still fresh, it can run a little warmer before it breaks in. Drive accordingly until then.

[dhs.buckley]

Originally Posted by Treeve

OK, so to get back on topic, you know your head gasket is backwards, but because a thermometer mounted somewhere completely different tells you a low temp you feel OK.

Except that a Windsor gasket mounted backwards would stop all the flow through one of your heads.

So apart from the fact that the heads are the hottest part of the engine, everyone here says the thermometer sitting miles away which isn't getting any hot water because you don't have any flow through one of the hot bits is fine.

I reckon a head gasket it cheap compared to blowing something more seriously. Check it properly, know for sure.

Treeve

Before removing the head I would put a laser temp gauge on the head and check several points to see if there are any hot points and compare the 2 heads. I found the laser temp gauge such a handy tool and they are not expensive anymore. I found that the temp gauge and thermostat where buggered on an old fairlane was reading 105c on the gauge in the car and with the laser on the thermostat and the temp sender it was actually 73c, new gauge and thermostat no more overheating problems.

[snakesaway]

Originally Posted by dhs.buckley

Before removing the head I would put a laser temp gauge on the head and check several points to see if there are any hot points and compare the 2 heads. I found the laser temp gauge such a handy tool and they are not expensive anymore. I found that the temp gauge and thermostat where buggered on an old fairlane was reading 105c on the gauge in the car and with the laser on the thermostat and the temp sender it was actually 73c, new gauge and thermostat no more overheating problems.

Oh yeah thats a really good point never thought of that. Thanks

[snakesaway]

Originally Posted by dhs.buckley

Before removing the head I would put a laser temp gauge on the head and check several points to see if there are any hot points and compare the 2 heads. I found the laser temp gauge such a handy tool and they are not expensive anymore. I found that the temp gauge and thermostat where buggered on an old fairlane was reading 105c on the gauge in the car and with the laser on the thermostat and the temp sender it was actually 73c, new gauge and thermostat no more overheating problems.

Well the temp test was interesting found about 30 degrees difference on the drivers side head at the back of the heads (this is the side I suspect the gasket is the wrong way around) but not much difference at the front of the heads.

So decent road test time drove it to work in the morning cool light traffic. So the temp gauge barely moved off the "0" of 180 F, crept up a smidge at the lights but not much. Next was the real test the drive home in the traffic outside temp was about 20 ish degress again not very hot. I did how ever sit in heavy traffic doing about 20-40 km/h for about 20 mins. Thermo fan on the temp got up to just shade before the "2" of the 210 F mark and stayed there (thankgod). Once I cleared the traffic and started moving again temp came back down to just above 180 F. So all good so far drove around in it most odf the weekend with no problems still no a particularly hot day. next big test is wait for a hot day and go for a drive and cross my fingers.

[07cob]

Originally Posted by snakesaway

Well the temp test was interesting found about 30 degrees difference on the drivers side head at the back of the heads (this is the side I suspect the gasket is the wrong way around) but not much difference at the front of the heads.

snakesaway

I put the gauge temp sender at the rear of the intake manifold at some stage and found the gauge read low. Very little heat regardless of driving. Moved the sender back to the usual place (front right) and temp was all back to normal.

Geof

[Jaydee]

The main problem with the temperature sender is it needs to be submerged in water. I have seen many overheating problems where the water was so low that it didn't register on the gauge. Or the customer has driven the car, it's overheated, they saw it on the gauge, pressed on, it's then lost all it's water and the gauge reading went back down. So they think it's alright. Then 5 to 10 minutes later, the engine starts to seize and the paint is melting of the block. The worst scenario, is that all the fluid leaks overnight, you then drive away with no water in the engine, the gauge doesn't register until it's to late. So what I've done is fit a airplane head temp gauge. It is a washer that has 2 bimetallic wires about 5 inches long and you screw the washer under the spark plug or a head bolt. As it heat up it sends a weak voltage signal to the gauge. No 12 volts needed. So if there is no water, it will still show the head temp. It's very accurate. It's a VDO gauge. It's really designed for air cooled engines. On my VW powered gyrocopter, I had one on either side cylinders.
JD

[snakesaway]

Originally Posted by Treeve

OK, so to get back on topic, you know your head gasket is backwards, but because a thermometer mounted somewhere completely different tells you a low temp you feel OK.

Except that a Windsor gasket mounted backwards would stop all the flow through one of your heads.

So apart from the fact that the heads are the hottest part of the engine, everyone here says the thermometer sitting miles away which isn't getting any hot water because you don't have any flow through one of the hot bits is fine.

I reckon a head gasket it cheap compared to blowing something more seriously. Check it properly, know for sure.

Treeve

Hi Treeve,

Hmm perhaps I should have continued on the path to pulling the heads off. I had the inlet and exhaust manifolds off and started thinking about rocker value clearances did some research and thought if I get this wrong things could go from bad to worse. When I had the inlet manifold off I could see the tell tale rusty color in the water jacket this also made me think the head gasket was ok.

I know the radiator was badly blocked so maybe that was the problem and they just used a different type of gasket when the engine was built. To my knowledge from speaking to the previous owner and the original builder the heads haven't been off since the engine was built (gasket tags are the same color as the block). The original owner had no problems with over heating.

You make a very valid point regarding the location of the temp sender, it is located on the passenger side of the block at the front of the inlet manifold (Edelbrock Performer RPM). The suspected reversed gasket is on the drivers side bank. Therefore if I am getting water flow past the temp gauge I am getting a false reading. I ran this theory past both mechanics and they said it wouldn't matter if i had a flow problem in the block it would over heat regardless.

So in summary still a bit confused, but you are right the only way to be sure is pull the heads off which I reckon is probably a job for a mechanic. The theory is easy but practice is often very different particularly when getting clearances right.

Thanks for your thoughts Treeve

[dave295]

[IMG][/IMG]

This is a photo of a Windsor head (buggered), plus two head gaskets. One gasket is upside down so you can see the difference.

Hope this helps you a bit.


Cheers
Dave

[dave295]

[IMG][/IMG]

[cg514]

hello Andrew i had a similliar problem on my big block cobra tried everything,
shrouds/ fans/ e waterpump/oil cooler each time cost money car never boiled
but i new something was not right took me 5 years to figure out .
dont drive the car very often and yep engine builder put head gasket on backwards,
i bought new set of gaskets then sat them on top of rocker covers and looked where
the tags were proud around outside of the head compared to the new ones sitting on top and you could tell without pulling the heads that passenger side was wrong now it never gets hot at all . so try and see before pulling heads it was really easy to spot in the end on the bib block anyway.
chris

[cg514]

hello Andrew i had a similliar problem on my big block cobra tried everything,
shrouds/ fans/ e waterpump/oil cooler each time cost money car never boiled
but i new something was not right took me 5 years to figure out .
dont drive the car very often and yep engine builder put head gasket on backwards,
i bought new set of gaskets then sat them on top of rocker covers and looked where
the tags were proud around outside of the head compared to the new ones sitting on top and you could tell without pulling the heads that passenger side was wrong now it never gets hot at all . so try and see before pulling heads it was really easy to spot in the end on the bib block anyway.
chris

[stephen low]

Andrew good to put a face to the name at the club meeting last night.

Trolling the forum for some info I spied this thread and thought I'd add some detail.

On the advice of my engine builder, Don Stafford, I've used a 90C water temp sender to trigger thermo fan on. Don's theory is these cars are generally under gunned for cooling so better the thermo comes on sooner rather than later.

I also had a thermo over-ride switch installed when the car was first wired to turn the fan on whenever I want. This may become somewhat redundant as I did previously have a high temp switch trigger but you never know.

I too plan on shrouding the radiator to maximise cooling air effect but currently the system has worked well for me.

Just some food for thought.

So how had you head gasket exploration gone?

Cheers

[snakesaway]

Originally Posted by stephen low

Andrew good to put a face to the name at the club meeting last night.

Trolling the forum for some info I spied this thread and thought I'd add some detail.

On the advice of my engine builder, Don Stafford, I've used a 90C water temp sender to trigger thermo fan on. Don's theory is these cars are generally under gunned for cooling so better the thermo comes on sooner rather than later.

I also had a thermo over-ride switch installed when the car was first wired to turn the fan on whenever I want. This may become somewhat redundant as I did previously have a high temp switch trigger but you never know.

I too plan on shrouding the radiator to maximise cooling air effect but currently the system has worked well for me.

Just some food for thought.

So how had you head gasket exploration gone?

Cheers

Hi Steve,

Yes it is good to put a face to your name as well. I currently have the termo switch for my Davies Craig fan set to about 85 C because that to was my theory better to have it run a bit more than not enough. The car was originally built with just a manual on/off switch for the fan so I have kept this in circuit just a precaution.

Getting the shroud back into the front of the nose around the radiator too I think has also helped. The temp comes back down quicker once I start moving after sitting at the lights.

After lots of research on the net and looking at gaskets, heads and blocks. I feel almost certain the gasket on the drivers side bank is backwards. As Rob has suggested he spoke to Don Stafford about this.

The car hasn't overheated since the new radiator core, water pump and fan. Its just the nagging thought I really should pull the heads and double check the head gasket to be 100% sure. So I spoke to Rob last night and he is busy for the next few weeks, once he has sorted out his current list of jobs He is going to help me pull the heads and check the gasket. we will do both sides and send the heads off to be crack tested being the car has overheated twice just to be sure.

Cheers

[stephen low]

Sounds like the right sort of plan, then you can be sure and tick those details off as issues if the problem wants to persist.

[snakesaway]

Curiosity and my uncle finally convinced me too grow a set and pull the heads off to check the head gasket to see if it was backwards (as Rob had suggested the man is never wrong). So as the head came off and I saw the gasket on backwards a huge sigh of relief followed by a loud cheer. Anyway the heads are away being crack tested and checked for warping hopefully all clear on both fronts. I am a bit nervous about getting the rocker right but really shouldn't be that hard as they are the non adjustable variety (gotta love hydraulic lifters) I just hope I have them back in time to have the car running for the club run Sunday.

cheers Andrew

[dhs.buckley]

Originally Posted by snakesaway

Curiosity and my uncle finally convinced me too grow a set and pull the heads off to check the head gasket to see if it was backwards as Rob had suggested the man is never wrong). I am sure you all could have heard the cheer on Saturday arvo. Anyway the head are away being crack tested and checked for warping hopefully all clear on both fronts. I am a bit nervous about getting the rocker right but really shouldn't be that hard as they are the non adjustable variety (gotta love hydraulic lifters) I just hope I have them back in time to have the car running for the club run Sunday.

cheers Andrew

So after all that was the Gasket on backwards?