Thermostat question 348

I have my engine out for a belt service, I was bored this winter so I thought that I would try it myself.

I'm getting ready to order my parts and the thermostat is just down right stupid expensive...

I looked at the parts cross refrence and see that some recommend a Lexas GS300 or X/19 thermostat, I didn't see any comments if it worked so anyone have comments, one way or the other? If the two work anyone know the years of the two cars so I can order it?

If no one knows if those work any idea on cross references?

 

I ordered this one with the gasket also: http://www.amazon.com/gp/product/B000C847BS/ref=oh_details_o01_s01_i01

I can't verify it will work since I didn't use it yet but for $20 I would rather have it for when I need it. It has better specs than listed in cross reference list. I am of the opinion it will be a fine replacement.

 

Does it need to be replaced?

Put it in a pan of water on the stove with a thermometer and watch what happens.

 

It does work, just thought that with it being so hard to replace with the engine in that I would replace it now. Are you thinking that maybe overkill?

 

I really don't see failures very often and there was a time when about a third of new thermostats were defective right out of the box. I wouldn't replace it if it still works and certainly would test a replacement before using it.

 

Sadly, I know! We've sent out too many replacements than I care to remember.

OP: Another suggestion -- if you're digging into the waterpump, I strongly recommend you pressure test it before reinstalling the engine into the car. If it leaks during the test, you'll simply be annoyed and have to re-do it. If it leaks once installed in the car, they'll hear your cursing all the way to Bemidji.

Somebody on Fchat posting pictures of a 348 pressure testing rig a few years back. It *might* have been ferrarioldman.


.

 

Thanks guys, I guess i didn't know of the high failure out of the box. I will keep the current one, it works great. I will be changing the pump and that good info on the testing idea, I will do a search to see the rig.

I have a good list started Daniel so I will get with you this week to place my parts order. This is the 3rd belt change with about 40K on the car. The water pump was not changed out prior as it has teh factory paint marks on the nuts.

Do you have the same thoughts on the pump as the t-stats, if it works well don't mess with it?

 

I have one for 355/360 pumps. The 348 is a bit different. I don't recall ever seeing a test fixture for one.
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Wow, I guess I was invisioning a tester with the pump on the engine.

With a 40K pump but not leaking, does this also fit into the "if it works don't mess with it" category in your mind? Not trying to cheap out just don't want leaks.

 

I replace with new or rebuilt (The Jordan Co., Mississippi) at each engine out service. Cheap insurance. No problems yet.
I paid $130 for my last thermostat from Ferrari. I would certainly be interested in learning if this Stant 14078 fits AND works.

 

I hate to break this to you but, that is not the correct t-stat. It may fit properly, but the temp rating on it is too low (180°).

The correct temp rating you want is 190°F. The engine has to run consistently above 176°F for the Motronic ECUs to get out of the secondary enrichment mapping. If you run that 180° thermostat is will be opening just 4° after the ECUs are going to normal fuel mapping, and then drop back into the secondary mapping as the engine cools from the early opening of t-stat. This is really going to screw with the how your engine runs, can cause the cats to prematurely get worn out = not a good idea.

Make sure you get a 190°F thermostat.

 

Thanks Ernie-

Have you found a non-Ferrari t-stat that works at the 190 degree range? This makes sense as my car always was running too low temp wise and seemed to always be running rich, maybe because the ECU's where kept it in secondary enrichment mapping. I was just going to reuse the old but now the search is on for 190 degree t-stat.

 

The one I have in my car is made by BEHR. You can see a pic of it in this link http://www.ferrarichat.com/forum/showpost.php?p=141805005&postcount=12
Got it from GT Car Parts.

 

Thanks Ernie- Is that GT Car Parts out of Phoenix, AZ? I looked on line but as you can imagine that is a pretty popular name for a parts company.

 

"Yuuuuuuup", the one out of Arizona.

 

I'm resurrecting this thread to add another data point to the thermostat discussions. Forgive the terse writing, as nitrile gloves don't make this easy.

My 348 had been running cool, around 170-ish, halfway between the 145 and the 190, since I replaced my water pump. I did not replace the OEM thermostat at the time, as it has worked find previously (and they are pretty easy to swap).

After following this thread and reading Goth's discussion on low temp issues, I ordered a new thermostat and pulled my OEM one to test it. I went with the BEHR mentioned in this thread.

OEM still looked fine, pin was not stuck and it had the protective gate around the pin. Could still be the original thermostat from 91.

I put them both in a pot and heated some water with a candy thermometer attached. I have the video, and maybe I'll post it later, but results were as follows:

OEM opened around 185, and remained quite open until the water was cooled to 165 and closed completely at 160.

The BEHR opened very close to the same time as the OEM, maybe 190. Close enough to where you can barely see a difference. The big delta, however, was on the closing temp and speed. The BEHR closed completely 175.

In this case, I think the OEM thermostat may simply be worn and sticking a bit, but as you can see, 15 degree difference on the close is significant, and makes me feel pretty good about the change.

I repeated the test a second time and achieved similar results.

Going to go put the new thermostat back in while I have some light left and will update on temps when the job is done.

 

That is a good test and great observation whyte! Knowing at what temp a thermostat closes, is just as important as what temp it opens. A 15 degree closing delta is a big difference, which can certainly affect fuel metering. Looking forward to the updates.

 

Don't let the wife catch you boiling your t-stat in her favorite cookwear.

 

It gives the stews a nice, sweet flavor.

Update: I ended up using the new gasket with the thermostat, which seemed a bit loose to me at the time, but I assumed it would seal up with some pressure. Installed all the hardware, tightened carefully to spread the gasket. I then filled and bled the coolant system.

Temps immediately looked better! Idle was 195 +/- 4 degrees for 30 minutes, even after I revved it up a few times. On the original thermostat, I could never see north of 180 or so at idle since I had the new water pump installed.

It was about this time I notice a few drips of coolant seeping from the bottom of the thermostat housing. I tried a bit more torque and another run, but still, small amounts of seepage. Buttoned her up and tried again the next day.

Day two I pulled the thermostat and the new gasket looked fine, but still, seemed a bit loose. The old gasket, when placed on the new thermostat, BARELY fits in the engine housing; you have to work it the gasket seated properly. The new gasket, in contrast, drops right in place with no effort.

Since my old gasket still looked great and was pliable, I decided to reuse it. To further hedge my bet, I cleaned all the surfaces and put a very thin bead of gray Permatex around the edge, not to interfere with the gasket, but just to ensure the edges seal on the off chance the gasket takes a few days to settle into place.

So far, things look good. There were some drips under the car this morning, but I believe those are just some leftover coolant drips finding their way to the ground.

Took the car for its first run today, so hoping it remains dry when I check on it after a few hours. Temps were solid 195 all the way, so in that regard, big success.

(P.s. Did anyone ever find a torque spec for the thermostat housing nuts? I looked in the manuals and online and never found anything. Ended up going with about 22 lb/ft, which is slightly less than the waterpump housing itself.)

 

What thermostat did you end up using ? BTW my work shop manual show a torque for the water pump bolts at 18.44 ft. lbs.

Brewman

 

22 lbs is a lot for that puny little M6 nylock nut. Use a 1/4 short ratchet, hand tight, and just a squid more. It is sealing your thermostat, not holding up the lid, and you already have grey RTV plus a gasket.

 

One key step in my years of race preparation was pressure testing the cooling system overnight with the tester that attached in place of the radiator pressure cap. Pumped to 25psi, if it didn't leak overnight it never leaked at the track.

Do it with undertray off.

Best,
Rob

Sent from my ADR6350 using Tapatalk 2

 

I was in the 20 ballpark.

Went with the BEHR mentioned previously in this thread from an outfit in Phoenix. I wouldn't be opposed to OEM again, as they appeared to be better build quality, but I'd definitely test the unit before it is installed.

 

This location effectively pressurizes the entire coolant system equally enough to test for leaks? I admittedly haven't looked at a diagram of the hoses, but I'm guessing this can bypass the thermostat and pressurize both sides, radiators, heater core, etc?