T-stat on its way out?

[alexandermf]

Wanna start off first by saying any trouble I've had with tstats going bad on my NA subies messes with the temp gauge and other wacko stuff...this on my tleg I'm not sure.

My heat on full blast with the engine warmed up whether it be vent, bilevel, heat, etc isnt toasty... More lukewarm
Checked my engine bay and no coolant leaks. Both top and lower rad were hot but the radiator itself wasn't hot(I could touch the top with barehands and barely warm. This was after a two hour drive through the mountain passes in about 20 degree weather.

I'd also like to state that I have cold air from outside it seems "leaking"/ coming into the cabin from the big black box underneath the glovebox, more specifically the left side of the black box that mates up to the next black part closer to the center. When I turn the level of air up on any hvac setting to anything past 2 I get a very audible vibration/shaking noise coming from leaky area. My dash was taken out and reinstalled for a wiring harness transfer and it might not have all been properly bolted together I'm thinking or I just need to reseal it somehow. Why is cold air coming out of it though and is it related to my shittay heat issue? The heats never been an issue before but lets see what you all think?

[Legacy777]

You might have a t-stat issue, but the cold temps might be keeping the radiator cool enough to touch. I would check the passenger side end tank near the top. That should be pretty hot since that's where the engine coolant comes out at.

Regarding your leaking outside air. Do you have air conditioning? If you don't or even if you do, I'd check to make sure the proper grommet was installed. If the evaporator core has been removed, then there won't be anything to plug the hole on the firewall or on the evaporator box, which would cause some issues. You should be able to look in the engine bay at the firewall and see what's there.

[alexandermf]

Gotcha.. ill check that out tomorrow. I was thinking in my head maybe since there is a leak area that it was causing cool air to mix with the hot air making it barely warm as it comes out the vents.

Yes I have ac and it works fine, we recharged it about a month ago but never touched the comp.

So you think maybe the tstat and not the heater core is a separate issue causing the not extremely hot heat? I'm not TOO worried now that winter is almost over but I'd like to fix it and def fix the horrible noise coming from the area. Also josh I'm not entirely sure its outside air leaking but its freaking cold and it blows towards the passengers feet whether its cold or hot outside

[alexandermf]

Here's some pics to help visualize my leaky area(s).

Pic 1: this is the actual part shaking and making the horrible noise as I turn air up past 2 on any setting. If I hold it in place with hand while the fan is up the noise and shake significantly decreases. It sits right above where the passengers right foot would be. Not sure the exact part and its function.


Pic 2 and close up: Leaky area number 1, comes from the grommet/foam gasket right in the middle. If I shove the bottom part of the black tray towards the top part the cold air stops comin out.



Pic 3: Leaky area number 2, you can literally see the half cm space where the two black plastic boxes should be coming together at the foam gasket, if I shove these pieces together the cold air stops coming out as well....


All these pics and cold air/leaks leads me to believe when my dash was put back together not everything got bolted back all together right causing these pieces not to rest together properly. As you can see in this next pic this bolt is completely missing which I think can correlate to the dash components not all sitting perfect cuz this bolt hole is at least an inch off from how it should be

Pic 4: missing left bolt/cock eyed dash to firewall



If this is offset it makes me think it could be part of or the entire culprit...?

[Legacy777]

The first pic is of the blower motor. Check the bolts to make sure they are tight. You can also remove it to make sure there's no gunk or leaves in there.

Regarding the leaking air, yeah it looks like the heater core assembly, which is after the evaporator core, is not aligned properly. That would most likely explain the cold air, but not sure if it would explain the temperature differences on the radiator.

[alexandermf]

Hmmm I may need to take all the dash bolts out then and loosen it into place and bolt all together so its squeezing the pieces together...gotta wait for a nice spring day! Hmmm ya the temp is throwing me. I may just replace the tstat since its a cheap replacement. Someone else suggested since both rad hoses get hot my tstat is good and my heater core might be clogged/blocked?

[Legacy777]

The heater core may have some blockage, as well as the radiator based on what you've mentioned. You could try flushing the system with water to see if that helps, but again, that may be a nice spring day type of work.

[jp233]

Yeah, pull the blower motor out and clean it all out. You will be able to see the evap core from there too after the blower motor is out.

Make sure that your drain hose coming from the bottom of the evap box is not clogged (this comes through the firewall and drops to the ground).... if a varmint tried to settle in there for the winter, then your evap box can clog up and won't heat/cool properly.... and you'll have mouse nest crap that gets wet and stinks. You can pull the evap box apart a little bit, and squeeze a tiny vacuum tube in there (you can buy an adapter that I think is only 1/4" round) to try and vac out any debris. Be careful, there are little metal clips that help seal the upper and lower halves of the evap box together -- there is one against the firewall that you have to reach up behind there and get out, and get back in.

If it's never been done before.... a full coolant flush with the acid rinse stuff would be good, and/or you may want to disconnect the heater core lines and rad separately in order to make sure that any gunk comes out of there. If you do that, since you have to drain the coolant anyways, it's a good idea to change the t-stat regardless. Pull the freeze plugs out of the engine too in order to make sure you get a good flush of everything out, then run it with straight water to clean out any remaining acid/flush solution.

[alexandermf]

^thnx for the detailed explanation, I will def have to wait for a warm spring day to do so! I have a couple other buddies who think its just my heater core clogged/blocked so we shall see, good thing winter is over and this problem is just now starting

[Legacy777]

There really aren't any freeze plugs on these engines. There are lower coolant passage hex plugs, but I wouldn't consider them freeze plugs. They can be a big pain to get out. Unless you start getting a lot of debris, you will be fine with just flushing everything through the water pump by removing the t-stat. If you have a lot of debris, you can remove the coolant passage plug on the driver's side. No need to really do that on the passenger side since it's right where the coolant pump is.