Engine running hot

[yatisr]

I just changed the distributor, plugs, plug leads and fuel filter in my 323I. The car runs smoothly but the engine gets hot in traffic (temperature gauge is at the 3/4 mark). It used to run fairly steadily with the temperature gauge at just under half or slightly above half in traffic. I have also changed the fan clutch. Could this be an ignition timing issue? An undetected exhaust leak?

For general information, the ambient temperature here in Malaysia is about 32C. So a hot running E21 is a cause for some worry.
Yatis

[Peter V.]

Hey,

Since you have changed the fan clutch. Is this working good? Please check your thermostat also.

Ofcourse timing can have a certain impact on temperature but not so extreem. A leaner mixture makes the engine temperature slightly higher.

[Jeroen]

You didn't make any other changes or adjustments? And the temperature problem started after the described work was performed? That is very important info for a correct analysis.

If that is the case, it is likely the fan clutch is at fault. These need to be stored upright and especially the old style clutch that is fitted with a 8mm bolt from the front is very sensitive. As BMW doesn't even store them correctly obtaining a good example is very difficult. Why was the clutch replaced in the first place?

[yatisr]

The fan clutch was changed in response to the temperature issue. It is therefore not part of the problem. Sorry Jeroen; my query did not make clear that the change of the fan clutch was a response to the temperature issue.

I think Peter's suggestion that the thermostat may be the issue may be the answer. I drove the car in to work yesterday with the air-conditioning going and the temperature gauge was close to the 3/4 mark in traffic. This morning, I drove the same route (as usual with the air conditioning on) and the temperature was just over the half mark on the gauge. Would this suggest an erratic thermostat?

[Jeroen]

OK clear. The issue is most likely caused by lack of flow. Either
1. air flow to cool down the coolant in the radiator, or
2. coolant flow

1. air flow can be limited by a A. obstruction: dirty or worn radiator and in your case even air con condenser that is in front of the rad. B. limited compensation: your new fan clutch also not being ok
2. coolant flow can be limited by A. a internally clogged radiator B. a worn water pump C. a bad thermostat that is not opening completely anymore

If you don't see any coolant consumption, and you only see temp running up in heavy traffic, there is a good chance the thermostat is at fault indeed. But as many of the fan clutches fail even when new, you need to check if it's engaging when hot, you should easily hear it's blowing louder than usually. Also check the radiator to make sure enough air can be blown through.

More info in the FAQ section: http://www.bmwe21.net/forum/viewtopic.php?f=38&t=13416

[yatisr]

Coolant level is fine. The radiator (a modified 3-core copper radiator) was recently flushed as part of the car's mandatory annual fluid change earlier this year. No problems were noted after the coolant was replaced. The water pump is new; it was changed when the timing belt was replaced this year. Again, no problems noted after this change. I am beginning to think that the culprit might be an erratic thermostat. I shall do battle with Kuala Lumpur traffic this evening and see what happens. I shall report the good, the bad and the ugly tomorrow. Hopefully, I won't have to call up the Automobile Association of Malaysia for help.

[Jeroen]

Thermostat or fan clutch it is then!

[yatisr]

I have not ruled out ignition timing and fuel mixture either.I drove home from work yesterday with the air conditioning going and the temperature crept up to near the 3/4 mark on the gauge. This morning while driving to work I did not use the air conditioning. Effectively, this meant that the electrical fan which runs with the air conditioning was off all the time. The temperature was above the half way mark on the gauge. Allowing for the fact that its cooler in the mornings, there is no significant difference in the engine temperature with or without the air conditioning going. In other words, taking one cooling fan out of the equation makes no difference to the engine temperature. I will check the ignition timing and fuel mixture on the weekend. If I don't get a result, the cooling system, including the fan clutch, thermostat and radiator, will have to be checked out next week by my mechanic.

[Jeroen]

That's why I always ask to go back to the situation of first occurrence of a problem. What changes were made, what work was done, what was adjusted. The ignition timing doesn't change by itself, but the vacuum advance/retard system does for example if you have a bad hose.

[yatisr]

The distributor, plugs and plug leads were changed just before the problem arose. The fan clutch was changed in response to the problem (see my first and second posts). Hence, timing will be my first port of call on the weekend. However, if these are alright, then the thermostat must be the likely culprit. The vacuum hoses and vacuum/retard system hoses are fine. They are regularly checked. I'll come back after the weekend with my findings.

[yatisr]

The thermostat it is. I will have it attended to this week. Thank you Peter and Jeroen for the accurate diagnosis.

[yatisr]

Changed the thermostat and radiator cap. Still running hot. Blocked radiator? The cooling system is flushed once a year. I do not see any sediment or scaling in the expansion tank.

[johne21]

The temperature sensor could be at fault giving a high/false reading, an easy change to eliminate it, also bad earth on the instrument cluster can give false readings.

[Jeroen]

Not sure about that as readings are ok in other situations but there's always a slight chance the sensor is off in a certain range. Still, as indicated originally, the fan clutch is still under suspicion. Is it the old or the new version?

[yatisr]

The fan clutch was purchased a few years ago from W&N. I presume that it must be the new version. It seems to be working fine, as was the old fan clutch. I have the same temperature issue with the old and new fan clutches and the old and new thermostats. So, I don't think that either the fan clutch or the thermostat is the problem.

I will check the temperature gauge and wiring. The temperature sensor was changed a couple of years ago. I will check it out too.

Does anyone suspect the radiator? It is flushed annually, sometimes more often. But could it still be partially blocked and in need of a proper service?