drtidmore

a 170 degree thermostat...SUCCESS!

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drtidmore    222

Has anyone figure out if any of the available 170 degree thermostats that appear the same as our 195/180 Stant thermostats are in fact mechanically the same.  I would love to get a tad lower that 180 but have decided that 160 may be a tad too low.  Thermostats are cheap enough, I may order up a couple and see if they are physically the same as ours.  I have found a 84-85 Grand National 3800 170 degree thermostat so that got me to wondering

Edited by drtidmore (see edit history)

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2seater    117

As far as I know, the t'stat from a Grand National is the same small body design as ours? I had never heard of a 170* design but the first 160* I purchased was from a Grand National vendor in Tennessee before there was anything available in the small body stat. Interesting idea.

 

What I found with the cooler 160* 'stat was a bit better engine performance, way back when, but there did seem to be a small mileage penalty. I do believe the earlier cars went to closed loop a bit later than the '90 that I work with. I would have to check the chip for the setting, but if memory serves, it was in the 140* range.

Edited by 2seater (see edit history)
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drtidmore    222

The 170 thermostat I have found also fits all the other 84-85 Buick with the 3800 engine.  I have ordered one and we shall see.

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89RedDarkGrey    252

With a lower temp you won't be cooking the condensation out of the oil very well anymore. In your climate an external trans cooler would be ideal, and make it easier to cool the engine. An added benefit of an external cooler is the added fluid capacity. An inline magnetic filter is also great to splice in.

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D-a-n-i-e-l    23

From experience, with a 160 thermostat, a three row radiator and my fans kicking on at 185/low and 190/high, in Hawaii my car would run around 165 at  hi-way speeds and would get back up to 185-190 while idling. That being said, I doubt there will be a issue getting rid of moisture in the oil.

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drtidmore    222
13 minutes ago, D-a-n-i-e-l said:

From experience, with a 160 thermostat, a three row radiator and my fans kicking on at 185/low and 190/high, in Hawaii my car would run around 165 at  hi-way speeds and would get back up to 185-190 while idling. That being said, I doubt there will be a issue getting rid of moisture in the oil.

Daniel's experience with the 160 thermostat is in line with what I found while running the cooling system, after a thorough flushing, a new radiator and a new water pump BUT without any thermostat installed.  I ran it without the thermostat for a week or so just to get a feel of the cooling capacity of the system.  I did this in the late Aug of last year when the outside temps were still running in the high 90s to low 100s outside, so I got a good reference point of near worst case.  I concur with Daniel on the moisture/oil concern plus my Reatta gets a nice stretch of highway speeds at least once a week when I run up to our daughters house. 

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2seater    117

I don't think it will be a big issue. Oil temperature is influenced by the coolant temp. but is not the only mechanism that heats the oil. It splashes on the pistons and cylinder walls, bypasses through the oil pressure regulator, bearing friction etc.. Oil is a major contributor to keeping the working parts of the engine cool. In cooler weather, it is better IMHO to get the coolant temperature up to help warm the oil and other reasons. It would be interesting to have an oil temp. gauge and see what the influence the cooling system has.

Edited by 2seater (see edit history)
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drtidmore    222

I know this will not be a definitive test of oil temp, but I am going to pull the oil dipstick after the engine is good and heat soaked and get a temp reading on it using my infrared thermometer.  I will do this before I pull the 180 degree thermostat out and then again, assuming it fits, after I install the 170 degree thermostat.

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drtidmore    222
12 hours ago, 89RedDarkGrey said:

Have you got an Infrared thermometer heat gun?  Just point it at the oil pan, trans cooler line, water neck, radiator, PS cooler, diagnose a catalytic converter, AC/heat temps, many uses. It would make your before and after experiments more definitive.

Yes, I have a high end infrared thermometer with dual LED pointers that allow me to focus the device at the exact focal point of the device.  I use it for a variety of purposes.  

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padgett    432

I believe the computer is "all in" by 160 but years ago I headed north for Christmas in a '90 Bonne with 3800. Got half past Tenn and it dropped out of lockup. Pull ed into a service area and everything was fine. Pulled out and did it again. Same Same, after the third time I figured out that the thermostat was stuck open and on the Interstate it would cool down until it hit a threshold and it would drop out of closed loop which disconnected the lockup.

 

Personally always run 180F SuperStats in 3800s and keep the engine under 190F

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drtidmore    222
11 hours ago, padgett said:

I believe the computer is "all in" by 160 but years ago I headed north for Christmas in a '90 Bonne with 3800. Got half past Tenn and it dropped out of lockup. Pull ed into a service area and everything was fine. Pulled out and did it again. Same Same, after the third time I figured out that the thermostat was stuck open and on the Interstate it would cool down until it hit a threshold and it would drop out of closed loop which disconnected the lockup.

 

This is the situation that make me leery of the 160 thermostat.  Hopefully the 170 that I have ordered will fit, as I think that will be a great range for the tranny as well as the engine emission system.  

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Ronnie    369
48 minutes ago, drtidmore said:

 

This is the situation that make me leery of the 160 thermostat.  Hopefully the 170 that I have ordered will fit, as I think that will be a great range for the tranny as well as the engine emission system.  

 

I've been watching this thread with interest. I hope the 170* thermostat works in our 3800 engines. I think it is what I would like to have in my car.

 

I have a 160^ thermostat in my car and fan controls that turn the fans on high at 190* and off at 176*. It has been that way for years. On the average summer day (that is when I do 90% of my driving) my engine runs at about 165-170 degrees at highway speeds.

 

The converter locks up in my '88 model at about 140*. The engine goes into closed loop at about 158-159 degrees. The converter locking above 140 degrees might be unique to my car or to '88 models. I don't know.

 

If I drive when the outside temperature is below about 45-50 degrees the thermostat will not maintain 160* to keep the engine warm enough for closed loop when moving at highway speeds. It hovers around 157-159*. I can tell gas mileage suffers. However, I can't feel a drop in performance of the engine in open loop. Rarely do I drive when the outside temperate is that low so it's not a problem for me. If someone drove in cold weather all the time it might be a problem. Perhaps an overly rich mixture for extended periods would be hard on the cat converter?

 

The cooling system on the Reatta is more than capable of keeping the 3800 cool if it is in good condition - even when sitting still in traffic. My car never goes over 190* in bumper to bumper traffic for miles with the 160* thermostat and the fan control setup I have. I'm very happy with the engine cooling I have other than it dropping down to low in really cold weather.

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drtidmore    222

Ronnie, 

My '89 also allows the converter to lock above 45 mph once the engine passes 145+/-  degrees and the emissions go into close loop around 160 degrees so it would appear that at least 88 & 89 were setup with the same parameters for those items.  

 

I have had the opportunity to take some infrared (gun type thermometer with dual beam laser to ensure proper focal length distance) measurements and it confirms that we really have NOTHING to worry about regarding the oil collecting moisture with a lower temp thermostat.  With the engine coolant at 180 (i.e. thermostat cycling the antifreeze flow) and verified by measuring the temp at the top of the thermostat housing, the oil at the end of the dip stick measured 235-240 degree which will obviously boil off any moisture.  At least initially I will leave my fan control setting alone at 185on/176off after I install the new thermostat but I likely will tweak it downward a tad to around 180on/170off depending on how the engine behaves running at 170 degrees.  

 

The 170 degree thermostat has shipped from Summit Racing,  so I should be able to determine if we have a new option within the next week or so.  

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2seater    117

I am glad you are doing this experiment, very useful information. Warm oil and cooler water sounds like a good combination.

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drtidmore    222

While waiting for the 170 degree thermostat to actually arrive, I have been doing some more cross referencing and I pretty well now know that it will not fit even though it is the correct one for the '84-'85 3800 Grand National.  Finally was able to find physical measurements and it is the old standard size not the slim-type used on our Reatta.  At least the cost was fairly trivial and it was worth the shot.  Looks like we are stuck with either 160, 180 or 195 thermostats.  

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2seater    117

You're right, apparently the design changed from the '85 GN to the '86-'87 intercooled models. I wonder if it could be trimmed down approx. 3/8" to drop in? It was an intriguing idea.

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drtidmore    222
12 hours ago, 2seater said:

You're right, apparently the design changed from the '85 GN to the '86-'87 intercooled models. I wonder if it could be trimmed down approx. 3/8" to drop in? It was an intriguing idea.

The thought of trimming it has crossed my mind.  I intend to investigate if there is any way to make it work, so I have not given up entirely.

 

11 hours ago, 89RedDarkGrey said:

How about this?

 

CARiD has many parts for us. Thermostat? What car and year? What temp you want? The cater to racing and modders.

The one I have inbound from Summit IS the HyperTech that you referenced.  It won't fit as designed due to the fact that the seating lip on Hyperstat is too large and I question, even if trimmed down, if the support arms for the lower section are NOT too wide as well.  It took me a lot of searching around before I finally found hard dimensional specs and that was when I immediately realized the problem.  Again, I am going to see if there is a way to modify the Hyperstat to fit, but I have my doubts

 

Here are pics of both types and you can see the difference.  

SafariScreenSnapz004.jpg

SafariScreenSnapz003.jpg

Edited by drtidmore
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Ronnie    369
47 minutes ago, drtidmore said:

The thought of trimming it has crossed my mind.  I intend to investigate if there is any way to make it work, so I have not given up entirely.

 

Is you start grinding on the flange to reduce the diameter I think you will find that the flange is actually two pieces (top and bottom sections) that are spot welded and/or crimped together.  If that is the case, enough grinding on the perimeter of the flange will cause the two parts to separate and release the guts guts of the thermostat. I hope you do find a solution so we can use a 170* thermostat.

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drtidmore    222
3 minutes ago, Ronnie said:

 

Is you start grinding on the flange to reduce the diameter

Ronnie,

Yes, I am aware of the issue you bring up and that is one of my concerns.  What I won't know until I have it in my hands is if there is room to shave roughly 3/16 (3/8 total reduction in diameter) off the flange without mechanically weakening where the lower section and flange are joined.  Another concern is the effective diameter of the lower section support arms.   I have found that the height above the flange should work as it is .67" where the OEM fit for the Reatta is .91".  I have not been able to find hard numbers to determine if the extension below the flange is more that the OEM allowed .91 (yes OEM design is same above and below the flange).  This is one of those situations where not a lot of cash or effort is involved, so I am going to see what can be done.

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2seater    117

It looks like the visible tabs hold the lower frame that supports the spring, but the flange itself is one layer. It does look like that lower frame may be too wide to drop in as mentioned. I hope you find a way :)

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padgett    432

Just for S&G the Reatta thermostat is marked 44mm

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drtidmore    222

SUCCESS!

The HyperTech Power Stat #1007 (I got mine from Summit Racing) arrived yesterday.  I looked at it and going on memory I was encouraged.  I did some quick measurements and realized that if I ground down the flange to the inner line of the original o-ring seat I would be close to the desired 44mm.  I set about reducing the flange diameter on my bench grinder earlier this afternoon.  First cut looked good, so I went ahead and drain out some antifreeze and pulled the 180 degree thermostat that I had been running.  On doing a first fit, I found that I was going to have to removed a tad more diameter.  I took several passes at reducing it until it just dropped into the thermostat housing like the original.  I used my dremel with a fine grit sanding drum to smooth the edges until I could run my finger along without catching on any burrs.  As you can see from the pics, this particular thermostat turned out to be an absolute dead ringer for the Reatta thermostat other than the larger flange.  After installation and adding back in the antifreeze, I cranked the engine and at exactly 170 degrees (CRT gauges) the thermostat opened.  I found that on low fans with the vehicle stationary (70 degrees ambient temp), with the AC on and the engine running about 2000 RPMs (i.e. to get it nice and hot), the engine temp climbed to the trip point (186 degrees) of my recently installed fan control mod.  As soon as the fans kicked into high, the temp fell back to 170 in pretty short order.  I decided to adjust the high speed trip point such that the fans now come on around 180 and return to low speed at 170.  This is perfect for the tranny and the AC loves the high speed fans running.  

 

So, we NOW have a 170 degree thermostat option, assuming you don't mind doing a bit of grinding on the HyperTech thermostat.  

 

As you can see the modified thermostat vs the 180 specific fit simply could not be closer to each other.  I likely will order up another HyperTech #1007 and modify it so as to have a spare.

 

IMG_3169.jpg

IMG_3168.jpg

IMG_3167.jpg

Edited by drtidmore (see edit history)
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