NSolace

Good eve!

I've just purchased a 99 TL. Pretty awesome, for what it's worth and I'm starting to appreciate Acuras overall. It's my second car (first being a Nissan Altima).

Anyways, the previous owner had mentioned that it was starting to have overheating problems and he suggested it was the fans.

After buying it I ran through what I could to diagnose the problem. The fans did appear to have been busted (both A/C & Radiator). So I bought new ones and installed them, now they run.

The previous owner also mentioned that he just replaced the radiator and it did look pretty solid (on the outside at least).

I had a pressure test done - no leaks.

One thing I noticed was that the fans wouldn't come on when they were supposed to. There's also a fairly noticeable switch in power IF they do trigger on. Usually the temp would reach to about 75%-ish before the radiator triggers. At that point, it doesn't seem to help much anyways.

Next I replaced the thermostat, the temp sensor and fan sensor. The temp sensor was actually melted and all jacked up. I did burp the system after installing those parts. After doing those replacements (couple of days ago) the overheating seemed like it was fixed and the fans were triggering at mid temp area, which I assume is when they should trigger.

Yet just now it started up again.

Thoughts on where I should head next?

01acls

Did you installed the thermostat with the Pin at 12 o'clock?

Check the rad cap for damage?

Feel for an obstruction inside the upper/lower rad hoses (when cold). Get a visual when possible.

Check the rad fan relay?

Are the fans running on the high speed mode when engine is hot?

Test the temperature sensor B.

When was the last time the water pump was changed?

NSolace

Yes.

I also changed the rad cap (forgot to mention, sorry).

I'll check that in the morning.

If the relay is bad, then wouldn't that prevent the fan from coming on at all?

Not sure I can tell the difference. They certainly sound loud, but still wouldn't know for sure.

There's two of them, eh? I just thought there was the one under the intake and near the EGR valve? Then there's the fan sensor connected to the thermostat area. Other than those two, what else?

Unfortunately I don't know, but if I imagine if the relays/sensors are a no go, then that's probably my next piece to check. D;

Fun facts:

There is an interesting thing happening with the power. Like I said in the top post, you can feel and see a switch in power (night time) when the fans trigger. In addition, when it overheats, holding the door window buttons up will create that whole power shift and stop the temp gauge from moving up. I know it's not healthy or anything, but I just thought that something like window scrolling stopping temp gauge would add evidence to an electrical problem?

A few days ago I also got P0300 random misfire codes. I'm still working on solving that, but rather than detail this topic, all I want to know is if random misfires can have anything to deal with overheating?

01acls

Relays go bad in different ways not just off. Ie. Intermittent.

Fans will be on high speed if you turn ac to max and recirculation set to on. Both fans will be loud and moving a lot of air some what windy.

Before you do anthing else clean the battery cables and inspect the ground strap; all grounding points. Especially if the car is from a wet state.

Misfires can cause more heat but it will depend on when it's misfiring.














I think you can test the temp sensor B by checking for continuity above a set tempurature. You can find the temp in the wire diagram.

01acls

TLer trash

Sounds stupid, but make sure they are both sucking air through the radiator and condenser, and not blowing air towards the bumper and grill. Pretty rare, but I've seen it happen, and I think someone on this forum had it happen as well.

NSolace

I'm just getting into work, so don't have time to respond to all. I'll get your points afterwards.

I just wanted to stop in and mention that it started to overheat while on my ride to work. This isn't typical, mind you. Usually I can manage a ride without overheating. The point being, however, was that I had popped the hood right after getting to work. I could put my hand on top of the plastic engine top and it was barely warm. So I thinking sensor or relays, perhaps something not making the temp gauge work right. I'm gonna burp the coolant a second time when I get home.

Thoughts?

01tl4tl

burp following the owner manual method, its special- make sure heater is on full hot and cabin fan on high when burping rad system

Have you replaced FAN SENSOR A, at the thermostat housing on a 99
Most common thing to go wrong and easiest to replace-
It will keep main -driver side- fan from running when needed, then run for 5-10 minutes after engine shut-down!

01tl4tl

there are 5 small braided ground wires from frame to engine and devices.
Remove and clean every one of those- replace as needed
The MAIN battery ground cable has been found to be loose INSIDE its connector- where it mounts to frame under battery tray!! ooops!
Odd electrical usually traces back to a bad ground, hopefully nothing else has gotten hurt
Stop doing things that make it worse!

In Arizona, how old is the battery??? ..3 years would be impressive in the heat

rcb2000

you have an air pocket in the coolant system and the sending unit and/or gauge is bad.

Are you basing the overheating on what you see on the gauge or actually seeing the cooling system releasing steam? also touch the metal not plastic or use a temp gun to know what the block's temp is and not worry about a piece of plastic that will not heat up to start with.

NSolace

Looks like I've got a lot to do when I get home.

Anyone have exact instructions for burping a 99 TL? If I recall, there's no bleeder valve?

The Adobe manual file that Acura gives is only loading the front index page. So that's not helping much

NSolace

Looks like it may be the thermostat I put in. The overheating happens while moving and goes down at idle. It could be air pockets, yet I'm not gonna waste more time.

I should've tested the part when I got it. Said it was brand new OEM, yet I assumed instead of dropping it in hot water.

I'll keep you guys posted.

rcb2000

ebay part?

01acls

Burping

Cold or cool engine

Start the car and set heater to highest temp (open heater valve)
Turn off engine
Remove rad cap
Top off coolant
Install rad cap only half way (first click only)
Run the car at idle untill the fans come on at least twice
Remove rad cap and top off coolant if require
Install rad cap to full lock (second click)
Fill overflow tank to max level
Finish

NSolace

Alright, so I solved it. I'll need another couple of days to know for sure but I believe the overheating was due to air bubbles.

Last night I took out the OEM thermostat again to test it, sure enough it works perfectly. So after re-installing I burped the system, this time for around 40mins. Afterwards I took it for a short spin with A/C on full blast and it was fine.

Today, my ride to and from work, was good. So far it's looking like a pass. I'll still need to put some more miles/cycles through to know for sure, but I'm positive as of now.

Thanks to everyone who responded with help & support! I means a lot.

01tl4tl

that's not the complete burping process posted above, besides heater set to highest temp you want the cabin fan on HIGH and open the windows to let heat escape the car. Above diy is missing the parts of 2000 rpm holds till fan cycles on and off, then idle- cking level - then 2000 again yadayada
Its posted from the book on here in several places- maybe even the diy section
plus in the owner book for the car
get a free owner book download with all its help at acura care Acura Owners Site | Exclusive Knowledge, Service, & Benefits need cars VIN number to register