Overheating CSi

[Dave B]

Folks,

My 1975 3.0 CSi has started to get quite hot very quickly. No leaks, levels all ok, but suddenly she does not like sitting in even fairly minor traffic. Dont think its air in the system.

Temp gauge has started to pint upwards and it has only been due to short journeys that it's not gone near the red or actually overheated.

I am thinking of changing the thermostat, but feel that it might be the viscous fan coupling. Even while hot the fan blades can be quite easily stopped using fingers. I thought it should be more difficult to stop?

Still got the red 5 blade fan. Keep this or change to the black fan with more blades. Have a fairly modern re-cored radiator, and the heating issue is a recent thing. Hoses were all changed in the last year.

Any help or advice would be appreciated.

 

[JhwShark]

It does sound like the fan clutch could use some fluid (Silicon); Toyota still sells the fluid as they have cars with this application. There is a procedure to refill it, I'll try and find it.

Essentially, you remove the fan clutch assembly, remove the rectangular thermo strip from the center (remember which side is out) uncovering a fill hole. Then while turning/spinning the fan (mounted to a bench or...) squirt in the silicon; let it come to a rest and do it again a couple of times. Reverse the procedure use a little clear sealant (not sure if it needs htv or rtv) on the thermo strip at the edge only, then reinstall.

By spinning the fan while filling you disperse fluid as far into the outer part of the clutch and just keep filling to full. The 9 blade fan is good choice as well. I still have my 5 though.
Jon

 

[MMercury]

Folks,

My 1975 3.0 CSi has started to get quite hot very quickly. No leaks, levels all ok, but suddenly she does not like sitting in even fairly minor traffic.

A few thoughts.

As has been suggested in other posts regarding this subject, you might want to double check that your gauge is reading correctly by the use of a point and shoot infared thermometer.

You also indicate the old style fan clutch may be showing signs of wear. If in doubt, two longer 10mm bolts can be employed to lock the fan in drive mode. This will obviously defeat the clutch, but if your temperatures remain in the "normal" zone while sitting in traffic - with the fan positively engaged, your question about the fan clutch will likely be answered.

Would not overlook the possibility of a lazy thermostat and/or a plugged radiator and/or an extremely loose water pump drive belt as a cause or contributing cause of overheating.

hth, good luck.

http://www.e9coupe.com/forum/showthread.php?t=6875

http://www.e9coupe.com/forum/showthread.php?t=4694

http://www.e9coupe.com/forum/showthread.php?t=6114

 

[sfdon]

I get several cars every year with the same issue- Always and I mean always check the small hose from the radiator to the expansion tank for positive flow. If it is clogged you will over heat very quickly. Be very cautious with the new fan clutches - I have returned 5 new clutches this year. Don't trust them....

 

[Dave B]

advice

Thanks very much gents - plenty for us to work with.