Discussion Engine overheats in 2nd gear

[bheeney2]

Ford Ka, 1.6 L Zetec Rocam, manufactured in Brazil. The engine is called a Duratech-8v (Rocam) in Europe.

the engine overheats after driving in 2nd gear and after the engine has reached its running temperature. So you can be driving normally along a highway and then enter a car park (where you will use 2nd gear a lot). When you turn off the engine it boils over. If however you pull over at the side of the road and only use 2nd gear to slow down then that is ok.

A very small amount of white smoke is seen over the engine between the engine and the bulkhead after overheating.

If you keep the engine running after you stop it is ok but at low idle it will still boil over. In heavy traffic that stops and starts it will boil over while on the road. If you coast that prevents it from happening. The fan and air conditioning run ok.

Adding anti-freeze makes a difference but it will still happen. The radiator was replaced. Only a small amount of water is lost when driving and it was not too bad before the radiator was replaced. Other attempts were made to try and fix it. I noticed a new thermostat left in the car so I assume that was tried too. The temperature gauge does not work.

The Rocam feature produces more torque so I would expect more cooling problems as well but these has become worse over the years.

 

[RLGL]

First: fix temp gauge
Second: do a leak down test on engine
Third : Pressure test Cooling system.

 

[bheeney2]

That sounds like sensible advice. Thanks.

 

[deadlyapp]

You may want to see if this is a common issue.with this engine as it very well might be. If there isn't a lot of fluid that is maintained in the engine for normal cooling, then putting additional load on the engine and then turning it off (not allowing the coolant to circulate back to radiator) could very well cause boil off of the coolant that is still trapped in the engine. Heavy load in other circumstances could do the same thing but should be less pronounced since the engine is still circulating coolant.

I'd check or replace the thermostat again, and a leak test of the coolant system isn't a bad idea.

 

[bheeney2]

The amount of circulating fluid in an engine is something I had not thought about.

 

[mindless1]

Another issue with being low on coolant is that if the thermostat is at a high point in the system, it may not even be submerged in coolant so it doesn't open, or it may be a bad t-stat.

You wrote "I noticed a new thermostat left in the car so I assume that was tried too. " Unless I am misunderstanding, that doesn't make sense. If there was a USED thermostat found, then I'd think, okay, this is the old one and a new one was put in. If there is a new one, it wouldn't make much sense to go to the trouble of swapping it in to replace an old one, then if the problem wasn't fixed, to take the new t-stat out and put the old one back in and just abandon the new one, UNLESS the person was super-greedy and tried to take it back for a refund and was denied because it had been used, but t-stats are usually pretty inexpensive, around $10 so most people wouldn't bother trying to take it out to get a mere $10 back.

Anyway, I don't think it has anything directly to do with 2nd gear, rather indirectly that the vehicle is going slower so there is less air pushed through the grill. Then again you wrote the fan and air conditioning run okay but did you check the radiator fan? It should definitely be running if it is overheating, but if the control circuit depends on a temperature sensor that has failed, that could cause this. I would have hoped that they designed it so that a sensor fault, defaults to always running the fan, but that hope doesn't necessarily make it true.

If it has overheated too much, for too long, you could also have more problems now like head gasket, warped head, cracked head. I would not drive it at all in a scenario where it might overheat, and once the problem is fixed, change the oil.

 

[JCH13]

I'm with mindless1, check to see if the radiator fan is running. If not... well... there you go. The fan is not needed at higher speeds, which is why you see things going bad at slow speeds. It's possible that the fan and temp gague are driven by the same sensor. The sensor could be bound in an air pocket or simply dead. One cause that explains all your symptoms is usually a good bet. Check it out.

 

[Scarpozzi]

White smoke in the exhaust can sometimes mean a blown head gasket. (burning water) Does the exhaust smell like coolant...it's like a sweet smell almost. You can also remove and inspect your plugs and try to spot coolant there. I agree with JCH13 about the radiator fan. If that's not kicking on/off than it can cause the radiator to be disfunctional. If you just had it replaced, make sure they hooked everything up correctly.

 

[bheeney2]

Then again you wrote the fan and air conditioning run okay but did you check the radiator fan?

I confused the heating fan and the radiator one. I meant the radiator fan is running when you stop the car. I want to see if it starts to run after a short distance driving to check if it comes on when it should.

Does the exhaust smell like coolant...it's like a sweet smell almost. You can also remove and inspect your plugs and try to spot coolant there.

With the repairs that have been done there is no coolant in the engine at this particular moment in time. This suggestion is something I will take note of for future use.

Sorry I cannot respond to all the suggestions that people have provided. It is more than I expected.

 

[MtnMan]

Radiator fan............

 

[bheeney2]

At the moment I am working on the assumption that the coolant temperature sensor is not working properly and that because of that the fan does not operate soon enough. I plan to replace the sensor and will see how it goes.

 

[bheeney2]

Replacing the sensor and ensuring there was no air pocket underneath it did not make any difference. The warning light does not iilluminate as well so this fault must be to do with the engine management module.

Recently after a short drive I parked the car and lifted the bonnet (hood) to check if the fan was running after a short distance (which it was). I could hear a noticeable tapping sound coming from the engine. (This was a sound I could not hear so well from inside the car.)

I decided to look into this and discovered it had something to do with the valve clearances. I then got the manual for the engine and discovered it has hydraulic tappets. The tapping sound usually means one of the hydraulic tappets needs to be cleaned or replaced.

It was recommended to me to have all the tappets replaced which I have had done. There is still a tapping sound (from the no 4 cylinder) which is hardly surprising given how long the problem has gone on for. Is the only solution to have the cylinder head replaced?

The tapping sound is heard when you start the engine and continues like that. After a few minutes and over the space of a few seconds the sound becomes noticeably louder. It also gets duller in tone. Does this indicate anything?

Is it worth while to use a synthetic oil? I drive about 4000 km a year. Less than half the trips are to the supermarket about 1 km away. The remainder are round trips of at least 100 km. I live in northern Mexico where the temperature does not fall below 15 ªC normally. The mileage on the car is 89,000 km (56,000 miles).

Thanks to all the people who suggested checking that the fan was operating the way it should otherwise I might not have noticed the other fault. The link between a tapping sound and the engine overheating is not an obvious one.

For those who are interested a tapping sound can be caused by a valve clearance that is too great. The clearance should be correct for the valve to open fully. If it is an exhaust valve that is not opening fully then not all of the hot exhaust is expelled from that cylinder during the upstroke of the piston. This could lead to an overheating engine. The tapping sound in my case meant one of the hydraulic tappets was not functioning properly so it was not taking up the valve clearance. The tappets have tiny oilways which can get clogged with dirt. The dirt usually comes from combustion products in the cylinder head which get past the piston rings. The oil might be ok - it is what it contains that is the problem. So if your engine has hydraulic tappets it is more important than usual to change your oil when it should be changed. It is also important to keep the oil topped up.

 

[bheeney2]

I should have added that the engine does not overheat anymore.