Temp rising whilst driving.

[omegaman]

I've nearly finished my restoration of 505H and I'm having a few teething issues. 

Firstly I had a new disc from SJ that was warped, had it machined true, was 0.1 out on one side and 0.2 out on the other.....brakes work fine now. 

Then I had some slack in the UJ's on one side and a bit of play in the rear wheel bearing. It took 10 tons of pressure to get the stub axle out! all sorted now. 

The final issue I'm having is the cooling system. I have all new hoses, 74 degree stat (I've checked it in boiling water. I flushed the original radiator which was in great shape. I've fitted 3 new fans and the otter switch is working as it should. The thermostat starts to open at 74deg, I can see the temp rise on the top hose using an IR thermometer. The fans come on and keep the temp gauge in the middle at idle. I have checked the timing at its correct and Vacuum advance is working correctly. I've also check the carbs and they are working as they should. 

When driving the temp climbs and sits just under the red. Top of the thermostat housing is around 98 deg, intake pipe to water pump is around 70. Top hose on rad is about 85 ( it's lower because I'm reading it from the rubber hose) outlet of the radiator is around 70. The fans are always on once driving and are pulling air through the rad in the right direction. Looking in the header tank I can see a strong flow into it, which increases with engine speed, so the pump must be ok. 

I don't really know what to try next. My thoughts are that the rad isn't capable of removing enough heat from the engine once its on the move. Has anyone else had an issue like this? did a new rad fix the issue? 

 

Thanks 

[omegaman]

https://ibb.co/ZYW3txJ

[drdoom]

A mate owning an early S1 recently recalled how it rarely activated the fans yet stayed at agreeable temperature despite having the early compact radiator. Your diligence provides plenty from which to muse, and I'd suggest the return coolant temperature is, if anything, amply cool. Perhaps the ignition timing is insufficiently advanced? 

[omegaman]

Timing is set at 10deg static and the vacuum advance is working correctly.

 

It's very strange, I had a thought that maybe I connected the return hose from the end of the head and the hose from the bottom of the header tank to the wrong connections.....I don't that would make a difference though.....I'm pretty sure I checked the diagram when I was putting it back together. 

 

 

[Gis]

The temps you measure don’t sound unreasonable for a normally running engine in my opinion. Inaccurate dash temp gauge would be my best guess. Are the veglia gauges powered by a voltage regulator like in the later 910 versions?

[omegaman]

If I park after driving for 5 mins then the temperature starts to rise above the high 90's and starts spitting out of the overflow, I don't think it should be at or slightly above 100deg just from gentle driving and in fairly cool air temperatures. 

I'm not sure about the voltage regulator.....the indicator stays at the same high level during driving at higher RPM's and at idle, highest temp was the header tank body at 104 deg, it has a summer 74deg stat in it. 

[omegaman]

If i have connected the head return pipe where the header tank should be connected (T's into the radiator return pipe just before the pump) then that would be like the thermostat bypass valve being stuck open which would allow hot water to go around and around the block.........I'll have to double check that. 

Edited September 23, 2023 by omegaman

[omegaman]

Ok I checked the hoses today and I think it's plumbed correctly. 

 

I have the header tank and heater return connected to the pipe leading to the water pump inlet and the rear head pipe connected to the heater feed. That does seem a bit odd though, if you had the fan off but heater valve on, then hot water loops around and back to the cool side of the pump. 

[drdoom]

There's limited flow possible through the heater system so I'd not expect the loop to be problematic, given the rest of the cooling system is on the job.

[omegaman]

Not really sure what to try next, a new rad is expensive move if the one on there is just as efficient. 

[drdoom]

But the return coolant temperature checks out well, so what's a new rad to offer?

[omegaman]

Well it can idle from cold and using the fans stay at normal temperature. Ignition advance is correct, water level is correct, fans work, head gasket is good.........but...once driving and under load, temps begin to rise and stay high. I can't read the coolant return temperature whilst driving, but I'm guessing it's higher than it should be, otherwise the engine wouldn't be so hot. 

 

So the only thing I can think of that would cause that, is an inefficient radiator. If anything, when light cruising and wind being forced through the rad, the temps should stay normal, they don't. 

 

I'll remove the rad and give it a chemical clean, maybe at some point in the past it got oil on the system and it's affecting the rads ability to dissipate heat. 

Edited September 26, 2023 by omegaman

[jep]

Head gasket leak? 

[omegaman]

Nope, checked that. 

[JimmytheTurbo]

Are you 100% sure thermostat is correct way round? Someone had that wrong recently.

What temp do your fans come on?

Have you checked they are sucking not blowing?

I had my old rad recored/ rebuilt. Was under £100 a few years back.

Edited September 26, 2023 by JimmytheTurbo

[omegaman]

Yep 🙂 definitely the correct way up in the housing, and I boiled it and checked the opening temp and kept it that way for 10 mins just to make sure it wasn't closing after a few minutes. 

Fans come on around 80 something, otter switch working fine, I fitted a relay to the fans to take the load off the switch. 

 

Fans pulling air through the radiator. 

[JimmytheTurbo]

Are you 100% sure the housing is round the correct way?

 

[peteyg]

Isn't the 74deg thermostat a bit low for Wiltshire? Have you tried the standard thermostat?

Pete

[omegaman]

Low? well it's a Federal car so it would have been standard over there. If it was over cooling then I may have considered swapping it for a higher temp one......as it's boiling over, I don't think the thermostat opening later would help matters. 

7 hours ago, JimmytheTurbo said:

Are you 100% sure the housing is round the correct way?

 

What do you mean housing? how can the housing be the wrong way around? If you mean is the thermostat in upside down? no it isn't 🙂

[omegaman]

@JimmytheTurboI just read that thread, I think that must be a later car. The 907 2.0 engine has the cold return pipe go into the side of the pump and the thermostat housing is all part of the same assembly. I guess you could stick the thermostat in the housing upside down but I have tested the stat and it was in the correct way up. 

[drdoom]

So is it the standalone thermostat as fitted to early Turbo or the more conventional drop in unit? Is there some fault with how the rad, pod and airdam are assembled? Insufficient airflow while underway could account for this state of things.

[semi42]

I had similar problems with my s2, firstly, it wasn’t plumbed in right, secondly it was airlocked, 

the best way I found to fill the system (do this when cold)is not by the expansion tank but to leave the cap on , remove the heater hose at the rear of the head , use a spare bit of loose hose and put that on the connector on the head. You should now hold the two open ends up high and pour the coolant in to one of the hoses until it overflows from the other. Quickly remove the spare and reconnect the original heater hose.

[omegaman]

"So is it the standalone thermostat as fitted to early Turbo or the more conventional drop in unit? Is there some fault with how the rad, pod and airdam are assembled? Insufficient airflow while underway could account for this state of things."

 

Drop in unit in the S1, the housing is part of the water pump. The front scoop is new and it's clear from obstructions. 

I removed the radiator this morning and used a central heating cleaner in it for an hour.....quite a lot of bits came out, I might give it another soak tomorrow. 

 

"the best way I found to fill the system (do this when cold)is not by the expansion tank but to leave the cap on , remove the heater hose at the rear of the head , use a spare bit of loose hose and put that on the connector on the head. You should now hold the two open ends up high and pour the coolant in to one of the hoses until it overflows from the other. Quickly remove the spare and reconnect the original heater hose."

Thanks for the tip, I don't think there is an airlock anywhere though......the entire system gets hot and the coolant is circulating. 

[omegaman]

Here is what came out after an hour of cleaning, not too bad but definitely not the best. 

 

[omegaman]

Well after a few more flushes and a bottle of limescale remove and a litre of white vinegar overnight.....finally it doesn't overheat. 

At idle now, as soon as the water is up to temp and the fans come on, they only stay on for 60 seconds and then shut off. There is way more heat being blown out from under the front wheel arch. Temp 80 deg out of the thermostat and at 58 at the pump return hose. 

 

I took it for a drive and the needle doesn't move now, when I pull over the temperature stays stable and the header tank is at 70 degrees, before it was 102.