Stuck thermostat?

2004 Suzuki Verona I-6 (I know, I know. But it's paid for, comfortable, drives nice, only has 80K miles, and only gets maybe 25 miles a week added).

Never had this happen on any vehicle, but the symptoms seem to fit a stat that is stuck open. I'd like to be sure my thinking is right.

Didn't really notice til it started getting cooler, but my temp gauge takes forever to reach normal and I have an error code about something not reaching desired operating temp. It will blow lukewarm air relatively quickly but needs to be driven at city speeds (25-30) about 5 miles, then left to idle before it hits normal and will blow hot. Then if I drive 5 miles straight home at 40-45 mph or so, the needle drops and heat is not as hot. Fans never run in the cooler weather anyway, but they would kick on when it was 90-100 and the gauge stayed at normal.

Tried a full on flush (twice) hoping it was just junk or something but no help. Last time I tried to give it a little nudge with a dowel, but no joy due to location. I could take it off and really mess with it, but if I go though all that I'd hate to have do it again in 2 months. This car is a real pita to work on in the engine bay. I may have to buy one, but because it's actually a part of the housing, they run about $45-50 plus tax.

Thoughts?

 

Of course there are all sorts of components under the hood that weren't there 30-40 years ago, so could be something else affecting it, but sure sounds like a thermostat to me too. They used to fail often enough that a lot of stations had an assortment of them right next to the wiper blades, but I assume they're a more reliable today, because I don't recall having to change one for a long time. I remember putting them and a thermometer in a pot of water on the stove to see if they were opening and at the right temperature, but seems that most of them are hard enough to get to today that it makes sense to just replace it while it's out.

 

I'd get a 2nd opinion on whether you can't use a generic thermostat on that unit before coughing up $50 for what should be a $7-$10 dollar outlay.

Anyway, getting that corrected so that your vehicle gets up to the correct running temperature will also improve your gas mileage.

 

Keep it simple. Take large piece of cardboard and set it in front of radiator. If you live in real cold area, even cover engine with blanket.
We had metal "blinds" in front of radiators back in 'ol country for winter time. I actually drove here with cardboard through entire winter on our then 84 Expo LRV
Will keep you warmer till it gets warmer outside and you can work on it.

 

Vermont...no generic stat would fit. This thing is several inches long and is permanently attached to the housing...Genuine Thermostat Assembly fits 2004-2006 Suzuki Verona 17600-86Z00 | eBay

The European models had a slightly different set-up with a separate housing.

I found a new one on Ebay for $28 + tax, free shipping. Thats a heck of a lot better.

Ukrbyk...it's not like it's freezing out or anything. Maybe at 1AM, but I'm not out driving then. Like I said, 25 miles a week maybe, all in town. I used to use the cardboard on my GTO that I could never get the cooling system right on. Even then, driving through NM in a snowstorm at 17 degrees, it didn't help a bit.

 

T-stat job is it then.
Coolant level is to spec, right?
Worked well for my Russky car and for 84 Expo LRV we had. The cardboard. Mof, come to think about it, wife's RX300 never really warmed up and she had half rad covered with cardboard.
Oh well, all cars are different.

 

Yeah, coolant is ok, no air in system before or after. Though it was a bear finding the right antifreeze. Couldn't find any low silicate stuff (HOAT) which would have worked and lasted longer. Had to go with regular old style stuff which will also work fine. I just need to remember to change it again before the silicates drop out of solution and become abrasive.

Guess I'll plan ahead and have them order some Zerex G05 concentrate. I'm not paying twice the price for diluted antifreeze.

 

Well, the 'stat and spark plug change is done. Even pulled the blower motor, cleaned it up, and cut the back of the plastic housing off, so I could lube the bearings. It would sometimes not start til I hit a good bump or whacked it with a tennis ball duct taped to a 3ft dowel (yes, I had one in the car). Also came to an almost immediate stop when shut off. I'll lube it every few months before I spend $250 on a new one.

Pulled hoses as needed (took over an hour just to get the spring clamp off the lower rad hose)
and flushed the old antifreeze and flush mix out several times. Fill with plain H2O, run, drain, fill run drain again.

Pulled the old stat and housing off (4 allen bolts). That was a pain since they had a bit of corrosion on the threads. Ever take a bolt out a 1/8-1/4 turn at a time? Leaning down in the engine bay to the bottom? Try 2. Even an allen adapter for a ratchet wouldn't work because of the length and angle. Got them out, rapped the housing a few times and it pulled right out. Cooling passages in block looked great and stat had no corrosion or damage. Cleaned old gasket off, wire brushed bolt threads and applied anti-seize. Ran a brass brush in bolt holes to clean as best I could. Put my new homemade gasket (wasn't paying $7+ shipping for new) on with some Permatex 2A, put the thing back in the engine, the bolts ran easily in finger tight, just 1 turn of the allen to tight.

Greased all nipples, put on hoses, slowly filled with 50/50 mix till last of air was out. Started and ran to leak test. No problems. Had to add maybe a pint of mix the next morning.


So here's the weird parts.

Weird part 1: When I got the new stat I noticed that basically it has a 1/2" bypass built right in the housing (the smaller of the 2 nipples in the pic at the link). It goes in to the block right where the stat sticks in, not blocked at all. Matter of fact, that's what allows the water in from the reservoir overflow to fill the block from the bottom and let air escape from the overflow hose on the rad. There's also a tiny hole in the stat plate like I'm used to seeing.
So, even with a blocked stat there will still be some flow when the engine is running. Not as much as the main hoses, but some.

Weird part B: When I pulled the housing and stat out, it was closed. I even checked by filling the large nipple with water...no leaks.

Weird part IIV: The old stat tested within a few degrees of the new one (I tested it too) when placed in a pan of cold water and brought to a boil, so I doubt it was stuck initially. It closed as it cooled, just like the new one.

Weird addendum a: Though it hasn't been super cold at all since then, yesterday was low 40's, rainy, and windy. The airflow started cool, then lukewarm, then warm, then as the gauge started to move it was quite warm. By the time I had gone 3 miles, it was hot and the gauge was at normal operating temp. It appears to be working normally. So I apparently replaced a working part and it's operating as expected?

The plug change was uneventful except for removal of the coils. Every other one had a wiring loom in the way of one of the bolts so I had to sorta work blind. Oh, that and the one plug and sleeve that were just dripping oil when I pulled them. Then I realized it was unused oil and if I missed the filler slightly, that's where it would end up. Whew, not an gasket leak or worse.

Check engine light is off after I cleared purge valve error and not reaching operating temp codes. May come back next purge cycle, cause it is pretty hard to fill the tank at full pump flow and I guess that valve error can cause it. Doesn't appear to be a big or complicated job if I can just blow the lines out and maybe the canister.

So, other than having to wait 10 days for the stat to be shipped 210 miles and trying to figure out the correct plug gap, pretty uneventful. My hands are barely scarred and I'm sure the sprained muscle in my back and the one in the front will heal up eventually.

Thanks for the help and reading this long conclusion to the story.