Replacing camshafts

[collins_dan]

I've had my S4 for about 4 years now and have always struggled with temp control. I put in an aluminum radiator with 10" electric fan, closed off all gaps between radiator and engine compartment and had the engine rebuilt including a new water pump. Its better, but it only takes a couple of traffic lights in quick succession and I can watch it creep up into really hot temps. When moving, no issues what so ever, which was not the case before the new radiator set-up and engine rebuild. The PO always suspected that the camshafts were the cause of the problem. They had been installed by the PPO, who had set the car up exclusively for autocrossing and night time dashes from the police. (There was a cut-off switch for all lights to improve its stealth abilities when being pursued.) I was thinking about replacing them with either Sprint camshafts or the Dave Bean 114r, as I want a fast road car, not an off-road racer. I priced out the 114r's yesterday and they were $370 each, which is out of my price range at this point.

So 2 questions for the group: 1) After all I've tried, does camshafts seem like the right direction to go. Could they be the cause of the heat build up that the idling water pump can't maintain? 2) Are there any sources of used camshafts that I could cost-effectively have re-ground to the Sprint or 114r spec?

I love driving the car and want to take it everywhere, but am limited by its inability to handle even lightest traffic/stop lights.

Thanks. Dan

[gjz30075]

I can't imagine the camshafts contributing to overheating. I'd look at the ignition timing, fuel mixture and possible collapsing of the lower radiator hose.

Greg Z
'72 Sprint

[collins_dan]

I think the timing and fuel mixture are OK, as its running well and idling evenly. I'll double check the lower hose. I replaced the twisted original hose with more of a right angle piece, which initially seemed to help, maybe as you say, its collapsing under heat. Thanks. Dan

[1964 S1]

I also doubt that the camshafts are the problem unless your Elan sits at a traffic light bouncing and goes hurumph hurumph hurumph with every revolution. If you've got a thermostat, take it out, drive the car as usual, and let us know the results...
Good Luck , Eric

editing and adding... just re-read your post.... do you know what your radiator capacity is ,,,, compared to the volume of an original rad?

[rgh0]

An engine that overheats when in stop start traffic is not due to high performance camshafts.

I would check the following after ensuring the ignition advance is in specification and not excessively advanced and the mixture is not lean as both these can lead to overheating. I also presume you have no head gasket leakage and are running the system full of coolant preferably with a overflow recovery bottle system that works properly

1. Is it really and truely overheating - the sensor and guage is potentially inaccurate and the sensor is also affected by heat of the exhaust system. Measure what is really happening in the cooling system using an independent and known accurate guage

2. Is the fan and radiator system working properly - in particular is where the fan is blowing covering where the water is flowing. A modern 10 inch ducted fan is sufficient if it covers the water flow area but if a substantial proportion of the water is flowing though the radiator in areas not covered by the fan then you will have problems. With a top to bottom flow wide radiator almost all of the flow goes down the left hand (exhaust) side of the radiator at low engine speeds if the fan does not cover this area then the engine will overheat in stop start traffic but be ok at higher engine speeds and car speeds

3. Finally is the pump circulating water properly - no twisted or kinked hoses and pump assembled correct - to much clearance between the impellor face and the housing will greatley reduce circulation especially at low engine speeds

regards
Rohan

[hatman]

Rohan's first observation is well made (ie are you sure that it's really overheating?) My own car's temp gauge needle used to move above the 100 mark in almost any traffic hold-ups and, on one occasion, hit 120, bang up against the stop - almost on to the oil pressure part of the gauge. (I have whole areas of grey hair that I can directly attribute to these experiences.) However, the rad never boiled over and the overflow pipe/catch bottle rarely warmed up, indicating that the system was in fact operating within acceptable limits.

I eventually deduced that the Speedy Cables-refurbed gauge was telling porkies so I pulled it apart and found that the needle needed a nudge to get it to drop back on to the zero stop. I re-positioned the needle to show a proper cold engine reading and it now tells a more believable (and re-assuring ) tale. Worth checking before you start pulling the whole lot apart.

[collins_dan]

Thanks for all the input. This is just what I was hoping for. A list of things to try.

In response to Rohan's suggestions:

#1, It doesn't overheat. I just watch the gauge go up and grow gray hair, like hatman! The thermostat has been replaced, but the gauge has not. The car did overheat for the PO, cracking the head, resulting in the purchase of a new head and the sale of the car to me, so I have always believed that the issue is real. Also, the fan can be controlled manually, or will come on automatically at 185F/85C due to an switch embedded in the upper right corner of the radiator. The fan always comes on right in sync with the temp gauge, despite the two not being connected, which has always made me feel that I am getting an accurate read on temp.

#2, The fan is centered, leaving the right and left side not covered, and alittle bit of top and bottom. I got the radiator from Dave Bean, its produced by Griffin. Its a crossflow. There, so I'm not sure if moving it off-center will help. I've attached a picture from another website that looks like it, but isn't the exact radiator I have.

#3, I will double check hoses. The top, I'm sure is fine. There isn't much hose there, as its an inline filler. The bottom, I will check. As I stated before, the lower has been greatly simplified vs the original. The water pump is new, Dave Bean cartridge style. It was installed by an experienced twin cam mechanic when the engine was rebuilt top to bottom.

The system is full of coolant and the overflow recovery system is working properly. Question on the ignition advance or mixture, wouldn't the car have more symptoms than just at idle? How would I know if the head gasket was leaking? Finally, how hot can I let the engine get before it will overheat?

Thanks for the advice, all.

Dan

[hatman]

The fan needs to be bang up against where the top hose feeds in as that's the hottest part of the rad and, as a result, the fan has maximum effect. Yours is set to blow through an already partially cooled area so you're compromising its efficiency.

[rgh0]

Generally to lean a mixture and to much advance to the degree that it causes your overheating symptoms would result in poor idle. Easy enough to check idle advance which should be 10 to 12 degrees. Generally extremely lean idle mixture would casue idle misfires and by itself should not cause the problem.

If the head gasket was leaking you would be getting coolant blown into the recovery system and not sucked back when the engine cools down - it does not sound like this is happening.


I would check a couple more things as it is not at all obvious what the problem is given your setup

1. Is the fan actually blowing air through the radiator versus running in the wrong direction. The fan shroud needs to be hard up against the radiator core for the fan to work properly?
2. Check the radiator outlet versus inlet temperatures - are you getting a substantial temperature drop across the radiator with radiator outlet near ambient - if so and engine is overheating then problem is low coolant circulation rate and this is either a blockage, faulty thermostat not fully opening or a pump assembly clearance problem.
3. If the check in 2 shows radiator outlet close to radiator inlet teperature then not enough air being blown through the radiator section where the water is flowing and you need to try repositioning the fan. Un bolt it and move it around and see what impact that has. If flow is only going through a small section of the radiator at idle then you should be able to measure the hot and cool sections of the radiator.

The set up you have should work fine - the challenge is just figuring out what the issue is.

cheers
Rohan

[collins_dan]

Thanks. I'll investigate and report back. I did check the lower hose. There are no twists or kinks, it seems in good shape, although maybe a little bit oval vs strictly round, so it could be collapsing and restricting flow. Just to better understand what I should be expecting, if I come to a traffic light with an engine temp of 87C and sit for 2 minutes with an outside engine temp of 30C, how much should the engine temp rise (at this temp the fan would be on)? And at what temp should I shut the car down to avoid overheating? Thanks. Dan

[rgh0]

Engine temperature should not really rise at all. In normal driving the fan should cut in and hold the temp steady. The engine should stay on the thermostat temeprature ( 80C?) while moving and rise up to fan cut in temperature (85C) when the car stops. It should go no higher as the fan should control it by cutting in and out at that temperature if all is working as intended.

A rise up to around 110 / 115 C is not a problem as with coolant and pressure cap it will not boil until around 120C plus. However you should never see this sort of rise when stopping after a period of normal driving.

cheers
Rohan

[alan71]

If you find the problem is the lower radiator hose Paul Matty sell a reinforced hose.
The one I removed you could easily squash flat between 2 fingers, the new one is quite rigid. I think it said Kevlar reinforced.

Alan

[collins_dan]

I am now very suspicious of the lower hose as it was exactly as you described, very easy to squash flat between 2 fingers. Truthfully, all else is new or newly setup. Dan

[paddy]

But is there someone hiding in your engine bay squashing it flat while you're waiting at lights?

[collins_dan]

I was thinking that the heat of the engine, heating it up and it collapsing.