Should the housing for the thermostat have a gasket?

I could see the metal-to-metal thermostat housing on the engine block developing a leak if a proper seal could not be created due to lack of a gasket. It's cheap and safe just to do both of them.

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1998 Riviera
Mods: 3.4" Intense MPS, 3.5" Tensioner Pulley, Gates Belts, 3.5" Intense FWI, 3" Hogan DP, Autolite 104's, 180* T-stat, STB, Silverstars, Park Avenue Ultra chromes, Infinity Speakers.
Soon: ZZP Stainless/Coated Powerlog, Coated Crossover, Hulkspeed Rear PEM.

Last edited by Eldo on Thu Jun 11, 2009 5:24 pm; edited 6 times in total

deekster_caddy wrote:

The ones I've taken apart with O-rings did NOT have a gasket OEM. It should only take one or the other.

Wow, I just found something I agree with Deekster on... razz

Seriously, for future viewers, here's my latest experience with a simple thermostat swap... First of all, I didn't realize how small these stats are! After only replacing V8 thermostats for the last 30 years, I can see how you'd want the "super-est" stat you could buy in here. 3.8 litres should have a bigger water outlet...

I just replaced the 195* stat on my supercharged '97 with a 180* Stant SuperStat. Everywhere I looked for the parts, I found both the flat gasket and the "O-Ring" listed. (Actually, it's really a ribbed and grooved trapezoid-ring...)

My older brother, who's been a mechanic for 30+ years, told me that he'd seen this gasket "schizophrenia" in these applications before. He's seen both the O-ring alone and the O-Ring with the gasket, and he's replaced them with only the O-Ring...

Now, when I looked at the parts I bought, I admit that I liked the Fram gasket with the orange rubber rib running around the middle of the sealing surface, and my motor currently had both the gasket and the O-Ring (but not the original Delco...)

However, as I disassembled the water outlet, I found that the lower bolt (the one where gravity would lead) had rust on all the threads above the manifold point. Also, there were stains on the side of the manifold below the water outlet... My brother and I believe that someone at GM was worried about the new O-Ring idea, and added a conventional gasket as insurance. But I think they bit themselves on the butt. oops

When they added the regular gasket, they didn't specify one where the inner circle was punched out to go around the rubber O-Ring. As such, instead of the O-Ring going "metal>rubber>metal", it goes "metal>rubber>paper>metal". It looks as though they created a cockeyed gasket 'crunch' that left a small path for coolant to weep out between the O-Ring, gasket, and the water outlet surface...

I used a proper, stiff, gasket-scraper to clean both surfaces (very important; the razor-blade types are too flexible, they can easily gouge the aluminum...) After I had nice smooth surfaces and had cleaned out the bore where the O-ring resides, I installed the new stat with only the O-Ring. Except for the fact that this style of seal gives a very short transition between 'tightening' and 'tight', and I hope I didn't strip anything, it has proven water-tight for the last 3 days...

I have one other, related, suggestion for parts: While working on the thermostat, it was virtually impossible to avoid wrecking the old, softened, "Supercharger Boost Control Solenoid Valve Air Filter"... Even with my local connections, this cheap little part was impossible to find without having to buy a whole bag of them.

My suggestion, which is very convenient when they have them in stock, is to buy the SuperStat, the O-Ring, the gasket (as a spare piece of insurance) and the filter, in one shipment from RockAuto.com... The convenience of getting everything including the filter delivered to you door is worth $16. However, I now say "when", because after I made my order, they called and said they didn't have any right now in the warehouse with the single filters. Now they sometimes add a line to the listing: "+ Sold in packs of 10; Price reflects cost of each individual item, not the pack"... The solenoid filter is at:
http://www.rockauto.com/catalog/x,carcode,1022050,parttype,5706

Finally, I'd point out that while it looks like a silly little part, this filter passes air every time you dip into the throttle. Whenever the vacuum before the supercharger drops, the bypass valve actuator closes the bypass valve, giving you boost. When you let off the gas, it returns to the bypass position. Because the Boost-Control side of the bypass-valve vacuum-pot is "inhaling" and exhaling with every change in throttle-position whenever the Boost Control Solenoid is not activated, which is most of the time, that filter is preventing grit from entering both the boost control solenoid valve and the bypass valve actuator. As they both cost in excess of $50, an extra buck is a good expenditure to ensure their long-term health...

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97 Riviera L67 - Desert Sandstone - Gutted AB Lid, Kool Blue AF, 180* SuperStat, Hogan 3" DP, ZZP 3.6" MPS; Sensa-Trac struts, Rockford-Fosgate 6x9's; Annoyance-Fixes: Express-Down delete, Full-time juice to Power Port, BRP-power to Glovebox lite, Brake-to-Shift delete, Console-compartment lite, Seat/Mirror Memory in any gear.

69 Wildcat Convertible, 430" QJet - Burgundy/Black - P/Win, P/Seat, P/Ant, Tilt, Cruise, Remote Trunk, Rallyes, AM/FM Mono!

I don't recall any complications regarding this filter you mention?

When I did my 180 t-stat, the old had both the o-ring and the flag gasket in place. No signs of leakage. I cleaned things up and used a new o-ring and flat gasket with the 180, and still have no leakage to report, for over a year.

_________________
Dave G
98 Riviera
Gutted, 3.8, 180, 104'S, front PEM, 3" DP & Cat, Caddy STB, GR2's. DHP 1.5

Quote:

When I did my 180 t-stat, the old had both the o-ring and the flag gasket in place. No signs of leakage. I cleaned things up and used a new o-ring and flat gasket with the 180, and still have no leakage to report, for over a year.

Same here. I've replaced my t-stat numerous times, last time being about 3 years ago. I always use both O-ring and paper gasket, never had a leakage issue.

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1998 Riv wrote:

I don't recall any complications regarding this filter you mention.

Really... Maybe it's just my big hands, but by the time I got all the scraping and cleaning done and had the new stat in, my filter had been mangled & torn. Was your filter indeed still in place? Here's what they look like,
http://farm4.static.flickr.com/3636/3549625122_f4b2375de7.jpg?v=0

Also:

UPDATE
Rock Auto called me an hour ago and told me that their inventory records were wrong, and the warehouse that sells these filters individually was out... They may get more in a month, but in the meantime I had to order via another supplier that only sells the GM bags of 10. When they get here I'll see what I have around for envelopes, and offer the leftovers to the group.

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97 Riviera L67 - Desert Sandstone - Gutted AB Lid, Kool Blue AF, 180* SuperStat, Hogan 3" DP, ZZP 3.6" MPS; Sensa-Trac struts, Rockford-Fosgate 6x9's; Annoyance-Fixes: Express-Down delete, Full-time juice to Power Port, BRP-power to Glovebox lite, Brake-to-Shift delete, Console-compartment lite, Seat/Mirror Memory in any gear.

69 Wildcat Convertible, 430" QJet - Burgundy/Black - P/Win, P/Seat, P/Ant, Tilt, Cruise, Remote Trunk, Rallyes, AM/FM Mono!

My BCS filter has been gone for over 100k miles. If you come across an extra, maybe help me out?

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Last edited by Eldo on Wed May 20, 2009 3:53 pm; edited 1 time in total

AA wrote:

My BCS filter has been gone for over 100k miles. If you come across an extra, maybe help me out?

Sure. After they get here, about a week, I'll keep 2 or 3 and list the extras in the For Sale section and notify this thread as well. If I have light enough padded envelopes (or tiny boxes?) I should be able to send 'em out for just a couple bucks each.

I guess you don't live in a dusty area... You've never had to replace the the BCS or the BBV even running without the filter?

I'll be busy for a few hours... My Hogan DP just arrived!

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97 Riviera L67 - Desert Sandstone - Gutted AB Lid, Kool Blue AF, 180* SuperStat, Hogan 3" DP, ZZP 3.6" MPS; Sensa-Trac struts, Rockford-Fosgate 6x9's; Annoyance-Fixes: Express-Down delete, Full-time juice to Power Port, BRP-power to Glovebox lite, Brake-to-Shift delete, Console-compartment lite, Seat/Mirror Memory in any gear.

69 Wildcat Convertible, 430" QJet - Burgundy/Black - P/Win, P/Seat, P/Ant, Tilt, Cruise, Remote Trunk, Rallyes, AM/FM Mono!

I need one also. Dibs please.
Thanks

_________________
98 Riv, 102K Miles, EBC, LS1 Ft.Calipers, STB, Addco Rr Sway Bar, 180* stat., SSAC Headers, HF Cat, 1.9's,
105# springs, MPS 3.4, DHP tuned by the Deekster.

I'll have to inspect, don't recall if the filter's there or not. I checked the AC Delco site, and it appears they can be directly ordered singly, but of course the shipping would likely be $7-$10...

_________________
Dave G
98 Riviera
Gutted, 3.8, 180, 104'S, front PEM, 3" DP & Cat, Caddy STB, GR2's. DHP 1.5

I'd probably take one also if you end up with spares. If it goes where I'm assuming it does, mine is also missing.

_________________
Dave G
98 Riviera
Gutted, 3.8, 180, 104'S, front PEM, 3" DP & Cat, Caddy STB, GR2's. DHP 1.5

1998 Riv wrote:

I'd probably take one also if you end up with spares. If it goes where I'm assuming it does, mine is also missing.

Check.

On the driver's (or stat) side of the solenoid, there are 2 nipples, 1 with a hose and one that should have the filter. If it's not there the clip that holds it probably is - I couldn't get mine off over the barb...
Of course, you have to pull the engine cover to see it. That's another little annoyance that I changed right away - I replaced the factory nut with a Dorman black plastic air cleaner wingnut that looks good with the ribbing on the top of the cover.

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97 Riviera L67 - Desert Sandstone - Gutted AB Lid, Kool Blue AF, 180* SuperStat, Hogan 3" DP, ZZP 3.6" MPS; Sensa-Trac struts, Rockford-Fosgate 6x9's; Annoyance-Fixes: Express-Down delete, Full-time juice to Power Port, BRP-power to Glovebox lite, Brake-to-Shift delete, Console-compartment lite, Seat/Mirror Memory in any gear.

69 Wildcat Convertible, 430" QJet - Burgundy/Black - P/Win, P/Seat, P/Ant, Tilt, Cruise, Remote Trunk, Rallyes, AM/FM Mono!

No worries, my cover hasn't been ON in 2 years. smile

Yep, the retainer is still on the nipple.

_________________
Dave G
98 Riviera
Gutted, 3.8, 180, 104'S, front PEM, 3" DP & Cat, Caddy STB, GR2's. DHP 1.5

Those friggin' filters aren't here yet...

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97 Riviera L67 - Desert Sandstone - Gutted AB Lid, Kool Blue AF, 180* SuperStat, Hogan 3" DP, ZZP 3.6" MPS; Sensa-Trac struts, Rockford-Fosgate 6x9's; Annoyance-Fixes: Express-Down delete, Full-time juice to Power Port, BRP-power to Glovebox lite, Brake-to-Shift delete, Console-compartment lite, Seat/Mirror Memory in any gear.

69 Wildcat Convertible, 430" QJet - Burgundy/Black - P/Win, P/Seat, P/Ant, Tilt, Cruise, Remote Trunk, Rallyes, AM/FM Mono!

Mine leaked like crazy without a gasket. Thats my input.

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1996 Riviera, 89k miles
Show: Tint ,Sherwood dash kit , PAU 17s , Magnaflow tips
Go: 1.9s ,FWI , 99+, Stage 1 TB, Plog + DP , 3.4" , Ported Gen III , decent tune.
Handlng: STB , Ma822s. STS 22mm rear sway bar.
Up next : KYB GR-2s ,

TonySmooth89 wrote:

Mine leaked like crazy without a gasket. Thats my input.

Did it have a good (new) O-ring and clean surfaces?

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'98 Buick Riviera; Gen V 3.25 pulley, N*, VS Cam, 180 stat, Custom PCM (Powrtuner), headers & HF cat , 42.5 lb inj.

Grant-built/PRJ/Thrasher trans 3.29 gears, 7/8 chain, zzp hardened IS