Motorad 413-192 - air relief or not

AbsoluteZero

Original poster
Member
Nov 21, 2011
211
Just received from Amazon a replacement t-stat for the Envoy. Amazon's description shows "air relief valve" however it's not apparent this unit does have the passage to allow air to escape when the t-stat is closed. I'm familiar with this feature on the OE stat. Those who have used this Motorad unit do you recall it having the air relief valve as described?

I found a photo showing the Motorad unit in this link: http://gmtnation.com/f25/running-cold-6857/#post124183 and it doesn't appear, in the photo, to be there.
 

Menthol

Member
Dec 8, 2011
177
AbsoluteZero said:
Just received from Amazon a replacement t-stat for the Envoy. Amazon's description shows "air relief valve" however it's not apparent this unit does have the passage to allow air to escape when the t-stat is closed. I'm familiar with this feature on the OE stat. Those who have used this Motorad unit do you recall it having the air relief valve as described?

I found a photo showing the Motorad unit in this link: http://gmtnation.com/f25/running-cold-6857/#post124183 and it doesn't appear, in the photo, to be there.

That was my pic. Ahh, so that was what that timy hole on the Stant was, I figured it was some sort of bypass. The 413-192 Motorad DID NOT have it. It's running fine at 195-197 for me.
 

Mooseman

Moderator
Dec 4, 2011
25,178
Ottawa, ON
That's to allow air out while filling the cooling system, preventing an air lock. Better to have it. Used to do an old hot rodder trick on older cars by drilling a small hole in the stat to bleed the air out. Otherwise you have to wait for the stat to open to completely fill the system and also risk overheating it because of the trapped air.
 

AbsoluteZero

Original poster
Member
Nov 21, 2011
211
The boss is cast into the housing where the vent should be located. I recall in the OE unit there was a ball in the vent that probably acted like a check valve. Any case it opened OK in boiling water so I'll use it. I found a contact link on Motorad's website and sent an inquiry about the non-existent air vent.

The box says it was made in Israel.

Also have an ECT sensor on it's way. Scangauge coolant temps are consistently reading in the low 180's but can vary sharply in a few seconds. However no trouble code yet.

Mooseman I thought about drilling a small hole in this new one but it would make it hard to return if a problem crops up.
 

jaguarjoe

Member
Nov 22, 2012
73
V-12 Jags had huge problems with air in the cooling system, to the point that when you changed coolant in them you did it on a hill with the nose up to get as much air as possible out of the system. There was also an elaborate scheme of vent tubes and a siphon jet to keep the air out. Vented t-stats were a key part of that system. FWIW- the hole had to be at the 12 o'clock position. With all that they still had air bubbles.
 

Mooseman

Moderator
Dec 4, 2011
25,178
Ottawa, ON
AbsoluteZero said:
Mooseman I thought about drilling a small hole in this new one but it would make it hard to return if a problem crops up.

Drilling a hole was before they started adding these bleed valves. I say that whatever stat you use, it should have it. I was just saying that in the old days I used to drill a hole in them to bleed the air.
 

AbsoluteZero

Original poster
Member
Nov 21, 2011
211
OK all is well! I had emailed Motorad but found an 888 number so I gave tech support a call. The rep said recently one of his cohorts told him their stats didn't have a bleed. He didn't believe it so he took one apart and said it's not visible but covered by the spring.... so I took the unit apart and sure enough there's a hole. The only thing I didn't understand is the spring was covering the hold such I don't think much air could bleed thru. So in the second photo I re-indexed the hole (arrow 1) so it would be near 12 o'clock and under the end of the spring (arrow 2) so air could escape.
Ignore the red RTV. Just holding the o-ring in place.

Any case now I know!
 

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Menthol

Member
Dec 8, 2011
177
AbsoluteZero said:
OK all is well! I had emailed Motorad but found an 888 number so I gave tech support a call. The rep said recently one of his cohorts told him their stats didn't have a bleed. He didn't believe it so he took one apart and said it's not visible but covered by the spring.... so I took the unit apart and sure enough there's a hole. The only thing I didn't understand is the spring was covering the hold such I don't think much air could bleed thru. So in the second photo I re-indexed the hole (arrow 1) so it would be near 12 o'clock and under the end of the spring (arrow 2) so air could escape.
Ignore the red RTV. Just holding the o-ring in place.

Any case now I know!

Damn, we thought it was blood. :rotfl: That's strange my same part # was stamped 89C/192F
 

AbsoluteZero

Original poster
Member
Nov 21, 2011
211
Menthol said:
That's strange my same part # was stamped 89C/192F

You know I didn't catch that. Further inspection 192° is marked on the assembly that compresses the spring but the pellet is clearly 87C. I sent an inquiry to Amazon. Amazon has been good about responding and even replacing problem parts. Monday I'll call Motorad's tech support and get their response.
My weekend installation is delayed anyhow..... UPS rescheduled the ECT sensor to Monday.
My guess is the pellet may be used in other models and the assembler grabbed one out of the wrong pile. Motorad doesn't list a 413-189
 

AbsoluteZero

Original poster
Member
Nov 21, 2011
211
I'll close the loop on this one for now. The install was delayed until Amazon sent a replacement ECT sensor. UPS lost the first one. What little driving I've done locally the coolant temp. as shown on my Scanguage settles out to 200°. This might be a little high but unless summer operating temps are way high I'm OK with it. The main thing is it doesn't vary more than a couple degrees while underway. Still don't know why Amazon list it as 89°C but the one I got has 87 on the pellet. I even called a US tech support person who check one of their units out of inventory and it was 87°C. Also got an email response from a VP of something. His office was in Canada. I had inquired about the no obvious vent. Any case called him and had a very pleasant conversation. I thought it was a nice touch. He confirmed the vent hole location
Hope it last for awhile. Not the most pleasant job to install. I did discover the rodents like the rubber insulator on the ECT sensor. Fortunately hadn't gotten into the wires yet.
 

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