Cooling Issue After Saxo 1.6 VTR Engine Swap: Need Advice

[idev99]

Hello fellow enthusiasts,

I recently swapped my Saxo's 1.0 engine for a 1.6 VTR from a Xsara. While performing the swap, I removed the heater core since the car is used for autocross. I connected the ends where the heater core usually connects to each other on the block. Additionally, I am using the Saxo's radiator as the Xsara's one does not fit.

After some testing, the engine is running quite hot, between 95°C and 105°C. As a side note, when I feel the radiator, it isn't very hot, well within a touchable range.

My question for those with more experience with these engines is:
Will blocking off the ports to the heater core instead of connecting them together help with cooling? My current thought is that the water is circulating too much through the block and not enough through the radiator, as the radiator stays relatively cool.

Thanks in advance.

[ozvtr]

Is this a TU5 engine?
I assume these temps are taken with the car not moving? What temp do you get with the car moving? Those temps are not that bad for a car not moving.
Take the thermostat out and check the number stamped on the end of the wax capsule.
Put the thermostat in a pot with a thermometer and water, raise the water temperature. Note the temperature at which the thermostat begins to open. Should be about 89'C IIRC. Or just replace the thermostat on spec.
What coolant temperature does the thermo fan kick in?

[wheeler]

You could just clamp the pipe on the current heater pipe temporarily to see if it runs cooler.
Yes check thermostat operation but considering the type of use the car is getting i would maybe consider just jamming the thermostat open.

[idev99]

Yes, it is a TU5 8V engine.

The temperatures I mentioned in my previous post were while driving. I have since closed off the heater core hose and completely removed the thermostat.

Today was the first race with the 1600 (it was 35°C outside). At idle, it stayed around 90°C, but during the race, the temperature gradually rose to 120°C by the last lap. I then immediately let it cool down by pouring cold water over the radiator. Note that this takes place on a field, so it involves 5 minutes of nearly constant full power demand with average RPMs around 5k. Maximum wheel speed on the straights is around 110 km/h on the speedometer, but the actual speed is more likely around 90 km/h, I would say.

The fan is hotwired. During testing (when it was 20°C outside), the engine cooled down quickly as soon as I turned on the fan. Today, I turned it on immediately upon starting to keep the temperature as low as possible.
But as I mentioned, it still got hot.

I know that Saxo's originally came with TU5 engines, was it a known issue for these to run a bit warmer? I can't find anything about different radiators for the different models.


Big thanks alraidy for your responces.

P.S.: How hot is too hot for these engines? I know they're quite tough, but I assume 120°C is borderline for causing damage?

[wheeler]

I have since closed off the heater core hose and completely removed the thermostat.

Does this engine have a 2 stage thermostat? If so you should never completely remove it, It should be jammed open to test.

[idev99]

Uh, I’m not really sure.

It’s one like this:

I just removed the thermostat from the housing so the water could always pass through.

[ozvtr]

P.S.: How hot is too hot for these engines? I know they're quite tough, but I assume 120°C is borderline for causing damage?

Yes. On the 16 valve, if the cylinder head temp gets to 120'C you get an over heat warning! This is usually a "loss of coolant" warning.

I'm not a big fan of removing the thermostat.

Are you running a coolant without Ethylene Glycol? You should not be running Glycol in a racing environment. For a number of reasons.

Water pump in good condition?

If the bottom hose of the radiator is also hot at the end of a run, the radiator is not up to the task. Could be a blockage?

[idev99]

As of currently, it is running on pure water, just rainwater. I was planning to add glycol to increase the boiling temp. Why not do this?

Why not remove the thermostat? I would rather have it be a little too cold than overheat...

The bottom radiator hose was indeed hot. That’s why I asked if the VTR/VTS Saxo's had cooling 'issues' from the factory.

I got a new radiator because the one from the 1.0 was smashed from a previous race, so it shouldn’t be blocked or anything. The radiator from the Xsara (the one orriginal to the engine) is significantly larger than a Saxo radiator, so I don’t know if this has anything to do with it?

I haven’t checked the water pump; it’s driven off the timing belt and is quite a lot of work to remove. But I’ve driven the Xsara for some time before removing the engine, and it never got hot, really. It was also used for autocross and never really reached above 105°C.

I did get the engine warning light after the first race, but I read somewhere it also lights up when the alternator is not charging. (Not 100% sure, though.) The belt broke, so I presume the light was from that.

Thanks again for your time and knowlage.

[ozvtr]

As of currently, it is running on pure water, just rainwater. I was planning to add glycol to increase the boiling temp. Why not do this?

Glycol is slippery. It's a hazard on a race track.

Glycol may increase the 'boiling point' but it is NOT as good as plain water as a coolant. If your engine gets to the boiling point of the glycol/water mix (under pressure), you are going to warp a head first!! Or in the very least, there is something VERY wrong!! STOP!!
You can get rust inhibiter coolant additives with 'wetting agents' and no glycol. Glycol is ONLY used as an antifreeze. If there is no chance of the coolant freezing, don't use it.

[ozvtr]

Why not remove the thermostat? I would rather have it be a little too cold than overheat...

Sometimes the coolant needs to go through the radiator slowly to give the air time to extract the heat from the coolant. If the coolant travels through the radiator too quickly it might not cool down enough. That's only a theory and it might not be applicable to YOUR case.

The bottom radiator hose was indeed hot. That’s why I asked if the VTR/VTS Saxo's had cooling 'issues' from the factory.

Thats not good. That means that the radiator is not dissipating enough heat out of the coolant before it goes back into the engine.
Is there anywhere the air could be going instead of into the radiator? Can you put 'blinkers' either side of the radiator to direct air into the radiator?

[Paul-R]

I thought that glycol was a wetting agent and reduced the surface tension of water. This means that the mixed liquid transfers heat more efficiently and actually cools better than pure water or even pure glycol.

It's surely only a hazard on the track when spilt? This would not be a normal circumstance and anyway could soon be dealt with by flushing with more water, unlike spilt oil.

[myglaren]

Not just the glycol either, coolant fluids have anti-corrosion additives and lubricants.

[idev99]

The nose of the car is pretty stock, apart from a steel tube that maybe blocks 5% of the radiator. There is also a mesh in front of it to stop any dirt or stones from damaging the radiator, but I don't think this blocks too much air. Also, the fan was always running.

My current thought on why the radiator couldn't keep up is that it was very hot outside (35°C) and that there is too much load on the engine for the speed I'm going. So, not enough wind to cool, and the wind from the fan is just not enough.

Blocking off a bit of the thermostat housing so less water can go through is an option, but in my mind, more water through the radiator is better. Definitely something I could try in the future.

I know water has better heat dissipation than water + glycol, but it boils faster. Steam does not dissipate heat at all, which is why I thought adding glycol might help.

Spillage won’t make the 'racetrack' any slipperier or cause danger; we race on a field (Belgian autocross is something completely different from the more well-known American autocross).

[wheeler]

Uh, I’m not really sure.

It’s one like this:

I just removed the thermostat from the housing so the water could always pass through.

If it looks exactly like that one then its a single stage thermostat.
Still, i would always rather jam it open than remove it completely.
I know what you are thinking about faster water flow however as said above it may now be flowing faster through the radiator that its not getting time to cool.
If you think about a combi boiler for getting hot water from your tap at home. If i open my hot water tap on full in my sink it takes much longer to heat up the water & it never comes out that hot, however if i only open the tap halfway the water heats up much faster & gets scalding hot. This is because the water is flowing slower through the heat exchanger so the burner has more time to heat the water.
The vehicle cooling system is the same principal but in reverse, on the car the heat exchanger is trying to cool the water but in the home boiler the heat exchanger its trying to heat the water.

[Stickyfinger]

"Sink" heat in the engine block/head will be a problem at low speeds/high revs.....adding a large Oil cooler should be considered.
Such heat build up is a big consideration with many off road 4x4 competition/trials builds.

I would also say (if not fitted) a well made/sealed @ the edges, radiator shroud should be fitted to prevent air spillage as this is also a big problem at low speed/high revs.