A310 running warm when city driving

Have recently fitted all heat shields in an effort to get the car running smoothly.

- Thermostat replaced with 81 degree
- Radiator replaced
- Fans replaced using 88/79 degree celcius activate/cutoff
- Various hoses replaced

The engine runs well on freeway at 25-3000 revs at approx 85 degrees. I assume waterpump works

When entering town temp jumps +10 deegree and climbs.... if fans kick in the temps drops.

I suspect poor circulation of coolant somehow. When looking at engine compartments of all other A310 i see the return hose of cool water running on right side of engine at a lower positioning. I have meaured temp on stainless pipe and it varies from 82 to 65 degrees.

Could the higher positioning load the pump too much ? Can the location over the engine cause the water to he heated by engine temp at city driving with many red lights ?

Lastly I have read another topic on a GTA overheating and noticed in the original service parts manual the is a V shaped metal plate over the radiator top. This part ( as well as many other) was missing when radiator was replaced.

I have now been working on the heating issue for 3 months and is getting rather frustrated as I just seem to move forward 5% with each step I take. Pefer not to waste more EUR on parts until I get an idea if I am totally down the wong alley or not.

Thanks in advance

BR Jan

I had a simillar problem on my Gta. The temperature stayed at 110. The problem was that the front radiator scoop was missing. After fiting temp stays at90, at only in traffic it goes at 105. I don’t know if the a310 has a front scoop for radiator, but you shoul check it out

I replaced the radiator and ther is no scoop.

Wrote to Simon Auto and no scoop or plate similar to the manual is avaiable

I think I will just buy some stainless plate and make my own to test. 500 grams in the front will not harm the weight of the car

Thanks for help

The radiator temperature switch on my car failed a few years ago resulting in climbing temperature when in slow traffic. Switching the aircon on activated the radiator fans and brought the temperature down. I replaced the switch and the system has performed correctly since. However, this occurrence made me more conscious of the cooling system and when I drive the car I tend to keep my eye on the temperature gauge even though it acts normally. Hence the interest in your questioning of what’s going on with your car.

Have recently fitted all heat shields in an effort to get the car running smoothly.
- Thermostat replaced with 81 degree
- Radiator replaced
- Fans replaced using 88/79 degree celcius activate/cutoff
- Various hoses replaced
The engine runs well on freeway at 25-3000 revs at approx 85 degrees. I assume waterpump works

I’ve been out in the car on the last two days when the ambient was about 27C. The temperature gauge reads 90C when driving at the legal 50 mph (and occasional 70 mph) on the country roads around where I live.

When entering town temp jumps +10 deegree and climbs.... if fans kick in the temps drops.

When in slow traffic or stationary the temperature in my car slowly rises to about 95C and then slowly falls back to 90C due to the fans cutting in. The cycle repeats if the car remains stationary or is in very slow traffic.
You say that when entering town yours jumps +10 degrees and climbs. Is the car still moving forward when this happens and what temperature does it climb to? When the fans cut in does the temperature fall back to 85C?

I suspect poor circulation of coolant somehow. When looking at engine compartments of all other A310 i see the return hose of cool water running on right side of engine at a lower positioning. I have meaured temp on stainless pipe and it varies from 82 to 65 degrees.
Could the higher positioning load the pump too much ? Can the location over the engine cause the water to he heated by engine temp at city driving with many red lights ?

The stainless return pipe on your car will not be original, but nothing wrong with that. It is nearer to the centreline of the engine than the hose on my car as can be seen in the photo. The original hose was perhaps a further 10 mm to the right. The stainless pipe on your car will probably have more heat input from the rocker cover than the hose on mine. Whether this would make much difference to the heat load to the system isn’t easy to quantify but I wouldn’t have thought that it would make much difference. After returning home in my car this week I measured the return hose temperature at 84C and the rocker cover at 91C. The actual numbers may be an approximation due to variations of infrared gun readings but the 7C difference might indicate that heat input from the rocker cover might be minimal. You could place a temporary insulator under the pipe, leaving the top of the pipe uncovered, to see if it makes any difference.
When you say the return pipe temperature varies between 82C and 65C presumably the 65C was after the engine was first started and the thermostat had not been open long or as the system was cooling down after the engine was stopped?

Lastly I have read another topic on a GTA overheating and noticed in the original service parts manual the is a V shaped metal plate over the radiator top. This part ( as well as many other) was missing when radiator was replaced.

Are you referring to a GTA parts manual or A310 parts manual? Presumably the A310. Attached is the A310 parts manual page for the radiator. Are you referring to the plate 6001000092 at the top? If this is missing from your car presumably the top of the radiator has been supported differently. This plate attaches to the body with the welded studs and nuts on the back of the plate. The radiator is bolted to the bottom of the plate. I used doorstops to give a soft attachment and made elongated holes in the radiator top vertical plate to allow for expansion. The nuts attaching the radiator were finger tight to allow the radiator top plate to move.
As you can see in the photo with the radiator temporarily in place above the radiator, there is a central gap where air can bypass the radiator. This gap is only partially filled by the ‘V’ bracket.
When I changed the radiator on my car, the plate 6000053604 on the left hand side in the parts manual was missing. I hadn’t really thought much about this plate until now but it looks as if it’s bolted to the body at the top of the air intake opening at the front and to the top of the radiator at its rear edge. Perhaps its purpose is to prevent some of the airflow going over the top of the radiator. I can’t think of any other purpose. It won’t be a support because the top support is by the other plate. I think I’ll make one to see if it makes any difference such as a quicker return to ‘normal’ temperature after increasing above 90C.
You may have noticed the foam 6000053677 in the parts manual, at the side of the radiator. There wasn’t any on my car but I’ve recently put foam in the gaps around mine. I can’t say I’ve noticed any change in the behaviour of the system but it will prevent some of the airflow bypassing the radiator.

Wrote to Simon Auto and no scoop or plate similar to the manual is avaiable
I think I will just buy some stainless plate and make my own to test. 500 grams in the front will not harm the weight of the car

See comments above.

As a matter of interest I looked at the car wiring diagram to remind myself what the dashboard gauge is showing. The temperature sender for the gauge is the one in the thermostat housing of the coolant pump. Here it is sensing the coolant temperature returning from the block/heads to the pump before exiting the pump and passing to the radiator, when the thermostat is open.
The temperature sensor in the block, next to cylinder 3, is the one that would activate the alert warning lamp on the dashboard. I couldn’t find any reference to the set point for this sensor but would imagine it’s similar to the 130C marking on the orange sector on the dashboard temperature gauge.

[John Sweet]

I have had 2 GTAs in my time and various other cars. My everyday car is a petrol turbocharged Skoda. One of the remarkable aspects of modern cars is no matter how hot or cold the weather is, how hard the air con is working, how fast I am going or how long I am stuck in traffic, the temp gauge stays dead centre.
The GTAs temps both moved around (once warm) depending on situation. My GTA Le Mans was stuck in a traffic jam for over an hour last year in 35°c. It got warm but fans regularly kicked in so never overheated. I know it got very hot because the unboxed stainless exhaust causes it to backfire regularly when it is very hot

John, My diesel Octavia is the same, gauge always stays at mid point, but a previous one that was leaking water did move a bit on the gauge before it overheated and oil pressure light came on. COOKED to death unfortunately.

Most modern cars have negative temperature coefficient sensors which have high resistance when cold, rapidly dropping when warm. The characteristic of these is very non-linear. Often from about 60 to 100 degrees there is little change in electrical resistance. They give the impression of fast warm up and very stable temperature on the gauge when warmed up. If the gauge does go up the scale, they really are over-heating.
In contrast the positive coefficient temp sensors fitted on GTAs, etc. have a near linear response with a relatively narrow range of change of resistance with temperature rise. Therefore there is a noticeable movement of the gauge from say 90 to 95 degrees when running slowly in traffic on hot days, and why you can see the effect of the cooling fan cutting in and restoring a lower temperature. The temp gauge in a GTA is much more sensitive instrument than most cars in the critical warmed up phase.
I had electrical contact problems with the temp gauge on my car (no surprise!) and thoroughly checked out the cooling system with an infra-red thermometer. Nothing untoward was going on. I just accept now that the needle moves a bit.

Carried out some more testing after the belt wheel has been fixed again. (belt driving water pump and generator).

The pipe temp is approx 65 after driving on freeway or highway. Higher when in city driving.

Also noted that engine is cooler when using high revs and warmer with steady low revs. I suspect poor water flow due to the 10 cm higher positioning of my pipe when comparing to original positioning. Maybe the pump can't lift the water high enough for a decent flow.

My conclusion is that I will need to get the original parts to test. Ordering custom made silicone hoses cost more than the original parts at Simon Auto so might as well go with the correct setup. Also noted that my thermostat is too low at 81 degrees compared to original 88 degrees.

Thanks for all your inputs

Carried out some more testing after the belt wheel has been fixed again. (belt driving water pump and generator).

Your comment ‘belt wheel has been fixed again’ just caught my eye. If you’re referring to the pump pulley has there been a problem with it? If it’s not standard it should still be smaller in diameter than the inner section of the crank pulley as the pump runs at a higher speed than the engine.

The pipe temp is approx 65 after driving on freeway or highway. Higher when in city driving.

This sounds lower than I would have thought but I’ve not measured the return line on mine immediately after stopping. When I stop outside the garage the fans always come on and the one time I did measure the temperature it was 84C.

I suspect poor water flow due to the 10 cm higher positioning of my pipe when comparing to original positioning. Maybe the pump can't lift the water high enough for a decent flow.

The height of your return pipe won’t affect the pump performance. The cooling system is a closed loop system and static head variations are cancelled out due to this. The pump only develops a head equivalent to the piping friction losses plus head losses through the block and head, radiator, thermostat and heater at a particular flow rate.

At one time there was a technical section on this website that contained a SAE technical paper about the PRV engine. This contained a short description of the pump plus its Head/Flow curves. I have a copy of this and attach screen shots of the curve and description. Unfortunately the text on the curve is mostly illegible but it might still be of interest as it shows what the pump is doing at different speeds and different system conditions.

The vertical axis is head and the horizontal axis, flowrate. The units of the head axis are illegible but the flowrate units look like dm3/min which is l/min. The last number on the right looks like 200.

The 3 lines that slope downwards to the right are pump Head/Flow lines for 3 different pump speeds. These will be pump rotational speeds not engine speeds as the pump rotates at a higher speed than the engine due to the pulley size differences. The speeds marked on the lines are illegible but the lower one will presumably be at engine idle speed, the middle one at some midrange speed and the top one possibly at redline engine speed.

The 2 lines that curve upwards from the origin are system resistance lines. The one on the right is marked ’Thermostat open’, presumably the one on the left is when the thermostat is closed. The pump will operate anywhere in the area between the two system resistance lines and the upper speed line. The particular head and flow developed by the pump within this area will be determined by the pump speed and whether the thermostat is closed, partially open or fully open. Once the engine is warmed up, the pump will operate close to or on the right hand system resistance line and will run up or down this line as the engine speed varies.

As a point of interest, it will be noted that the 2 system resistance lines run through the graph origin (0,0). This verifies that the pump only operates against friction losses in the pipes and head losses in the equipment, which are proportional to fluid velocity squared. If the pump had to also accommodate static head in the system then the 2 system resistance lines would, at zero flowrate, have started part way up the head axis by an amount equal to the static head.

My conclusion is that I will need to get the original parts to test. Ordering custom made silicone hoses cost more than the original parts at Simon Auto so might as well go with the correct setup. Also noted that my thermostat is too low at 81 degrees compared to original 88 degrees.

If you did replace the stainless return pipe with hose then you would have to introduce the short steel pipe that is attached to the right hand exhaust hanger which acts as a support for the long flexible and the short flexible at the pump return connection. You can see this in the photo of my car and is part number 6000056904 in the attached parts list page.

Looking at the photo of your car, as the horizontal section of the return pipe is higher up the rocker cover than standard, it’s also higher relative to the pump return connection. Can’t see how the pipe is routed to the left of the exhaust hanger but, after the bend, the pipe is sloping down towards the pump. As you know the pump return connection slopes upwards so a high point near the pump return connection is unavoidable. On my car, and others I’ve seen, the high point is just at the short steel pipe at the exhaust hanger. Before that short pipe the horizontal return hose is lower whereas on your car it looks as if it’s higher. This is shown in the photo of my engine.

Possibly the return line on your car has more of a potential for air locking than the standard arrangement. It’s difficult to know whether the pump could clear air from the pipe once it starts rotating, but just a thought. Might not lead to anything but the 65C return temperature you mentioned presumably was measured on the top of the pipe. Might be worth measuring it on the bottom of the pipe at the same time to see if there’s any difference. If air is trapped in this pipe I guess you could have a screwed boss welded at its highest point to act as an additional vent connection. As I said, this might not lead to anything but just thinking out loud.