Overheats only in 90 degree weather with AC

[99_cima]

hey guys,

I have done quite a bit of searching on this subject, I have found some information but I have a few questions regarding such info. ok so before I start my vehicle is a

-1999 Q45t with 200k miles.

I bought it last winter so im not new to the Q45. This summer it started reaching mid 90's in temperature. Before now I have had 0 cooling issues, but if its above 90 degrees outside the car runs fine. If its above 90 and I turn the AC on my car overheats something crucial. Fun fact: if i turn the heat on for overheating recovery temp will go back down and if i keep the air off after it has gone down it will stay down.

SO I thought the system was clogged to where it could take the extra load of the AC being on. . . well thats a big negative. Long story short . ..

-changed the Thermostat
-flushed the system out (no crap came out)
-burped the system with new coolant
-checked for leaks
-replaced the rad caps

I am out of options. Upon my research through these forums I noticed what someone said about the fan clutch. What was said that if you run the car to op-temp that you wont be able to spin the fan but for a fraction of a rotation. From this stems my very serious question.
My mechanical fan does not turn off, is it suppose to? It stays on constantly. Did my fan clutch give out?

Also I notice a slight wobble to the fan is this normal?

A very appreciative thanks in advance to everyone that makes a suggestion or comment.

[BCC93QT]

Typically if the fan blade wobbles it is a bad fan clutch. Replace the clutch before you have pieces brake and possibly shoot through your radiator. It should not overheat due to a wobbling fan so i believe the wobbling resulted in killing your water pump bearing. Replace fan clutch, water pump. I would not rely on the dummy gauge on your dash cluster.

[99_cima]

thank you hoss. . .ya i hear that alot about the interior gauge .. . if the water pump was in fact bad it would overheat all the time. I can drive the car for hours without overheating but only when the AC is on it goes nuts

[Skibane]

Upon my research through these forums I noticed what someone said about the fan clutch. What was said that if you run the car to op-temp that you wont be able to spin the fan but for a fraction of a rotation.

Correct. When the engine is hot, the fan clutch makes a solid mechanical connection between the water pump pulley and the mechanical fan, so the fan spins at full engine speed.

When the engine is cool, the fan clutch only makes a loose mechanical connection between the pulley and fan, so the fan only spins at a small fraction of engine speed - Essentially, it's just freewheeling.

If the clutch is good, when the engine is hot, you won't be able to spin the fan by hand for more than a fraction of a revolution - The clutch's tight connection to the water pump pulley causes too much drag.

If the clutch is bad, when the engine is hot, the fan will be pretty easy to spin by hand, because the clutch has lost its ability to make a tight mechanical connection to the water pump pulley.

My mechanical fan does not turn off, is it suppose to? It stays on constantly. Did my fan clutch give out?

The fan clutch never completely disconnects the fan from the water pump pulley, so the fan never stops spinning altogether - It just spins more slowly when the engine is cool.

[elwesso]

You could try changing the fan clutch, that will definitely help, but I bet you need to replace you radiator. After 200k miles it's probably pretty gummed up especially if you haven't replaced it. They're really not that expensive, look for an all-metal CSF radiator, they can be had for under $200, and install is very easy.

[N/A Q45]

I don't know if this was mentioned but check the electric fan. It's a bad setup stock to start with even if it is working, make sure that your rad and a/c cooler are not pluged up and not allowing air to flow through. You can have all the best fans in the word but if the rad fins are pluged with things like dirt/bugs or a bird (in the case of one of my q45s) the fans won't do sh-t.

[Skibane]

You can have all the best fans in the word but if the rad fins are pluged with things like dirt/bugs or a bird (in the case of one of my q45s) the fans won't do sh-t.

Yep - You'd be surprised at how much crap can get trapped between the back of the A/C condenser and the front of the radiator - And there's no good way of cleaning it without pulling the radiator.

The front of mine looked like this, at only 75K miles.



If I hadn't pulled the radiator out to install an auxiliary ATF cooler, I would have never noticed - The radiator looked perfectly normal from the engine side.

[BCC93QT]

Give us some good pics mang! I think the better looking Q you have the more this forum wants to help.

[99_cima]

hahahah ok well here you go




hhhaahha ok enough of that. . so I took out my radiator and to my displeasure. . I see this, and maybe its my overheating cause


I was also thinking maybe the belts are loose. Im gonna have to check after I get off work. . needless to say rad wasn't clogged did have road crap all on the front and it looks as if the fan hit it which makes sense because my clutch went bad and was wobbling pretty harshly. Replaced it but to no avail, then pulled the rad. I tried to give it a temp fix by pulling some of the fins out but ran out of patience lol it runs for about 30 mins without overheating. this may be my issue. Anything else I could be missing? need some overview

[99_cima]

Give us some good pics mang! I think the better looking Q you have the more this forum wants to help.

See above reply lol

[N/A Q45]

hahahah ok well here you go




hhhaahha ok enough of that. . so I took out my radiator and to my displeasure. . I see this, and maybe its my overheating cause


I was also thinking maybe the belts are loose. Im gonna have to check after I get off work. . needless to say rad wasn't clogged did have road crap all on the front and it looks as if the fan hit it which makes sense because my clutch went bad and was wobbling pretty harshly. Replaced it but to no avail, then pulled the rad. I tried to give it a temp fix by pulling some of the fins out but ran out of patience lol it runs for about 30 mins without overheating. this may be my issue. Anything else I could be missing? need some overview

I'd have to say you found it . That is really, really, really bad. Looks like about 70% of the rad has no air flow.

[99_cima]

[/quote]I'd have to say you found it . That is really, really, really bad. Looks like about 70% of the rad has no air flow.[/quote]

hahah yaaaaa. So this was the first thing I "checked", Id say I missed this because the fan shroud was in the way and the fan. Good thing I decided to take it out.

[Skibane]

hhhaahha ok enough of that. . so I took out my radiator and to my displeasure. . I see this, and maybe its my overheating cause


it looks as if the fan hit it

Sheesh - I don't know what the hell happened there - but I can't see how a wobbly fan could possibly hit the radiator in some of those spots!

It almost looks like someone got really stupid or careless when working on a belt, water pump or fan clutch.

ETA: Did you find any pieces of dead cat in there?