OEM vs. Aftermarket Thermostat - Coolant System Maintenance (1 Viewer)

[94SRUNNER]

Folks,

Has anyone had any experience comparing OEM thermostats verses Aftermarket thermostats? Our 100 currently is running a NAPA thermostat and am getting ScanGauge coolant temps of between 198 and 202* in our current midwest heat wave. Occasionally it will hit 204-206* pulling long hills, but quickly drops back down. The system is in need of a refresh as it is running older Prestone coolant and the radiator is original. I've got an OEM thermostat unit on order, but wanted to pose the question.

As for the radiator, mine is original and in fair shape. However, I have noticed that there is a decent size area of fins that have been bent over, seemingly impeding airflow. I surmise that this damage occurred when the TB service was completed. Would it be worth the time going through and "unbending" the damaged fins.

Thoughts?

Thanks

 

[94SRUNNER]

This evening I pulled the Napa thermostat and installed the OEM thermostat. I’ve included pictures below to compare the two. Napa on the left and OEM on the right. Quite a difference in design IMO.

 

[Spike555]

I have a aftermarket brand thermostat, I do not know the brand as I ordered it off Amazon. But it is a well known aftermarket brand that I trust.

Have your engine temps changed now?

A bad/weak radiator cap can cause higher engine temps.

Bent cooling fins can raise engine temps, depending on how many are bent I wouldn't worry about it. You might cause more harm trying to straighten them. There is a special "comb" that is used for that.

 

[94SRUNNER]

I did not take it on much of a drive. I spent about 20-30 minutes letting it idle with the cap off and the front end elevated to bleed off any air in the system. It only ever got to 188*.

About two weeks ago when I installed the Napa thermostat I did the same procedure and the temps topped out at about 197* during the bleeding process.

I’ll follow up once I’ve had a full drive cycle to see if temps have changed.

Additionally I have a new OEM radiator cap on its way.

 

[outdoorsman]

I would not recommend trying to bend fins back.

I always go with the OEM thermostat and change them with the water pump while doing the timing belt every 90k.

I don’t go with OEM on the radiators because of the crazy price from MR T. Denso is an acceptable replacement for the radiator.

180k is a good theashold to think about replacing the radiator for PM.

 

[94SRUNNER]

Update...

I went for a nice long drive to test out the newly installed OEM thermostat. No highway driving, but about a dozen miles of stop and go city driving. I am now getting ScanGauge coolant temps of between 188 and 193*. I am cautiously optimistic. We'll turn some highway miles tomorrow and see how temps look.

 

[Dwight S]

I had an aftermarket thermostat in mine and had temps at 197-207 and occasionally 211 with the scan-gauge. I noticed my radiator was filthy and weeping along the side tank and decided to replace it with a new Denso along with a new radiator cap. Didn't see any change in temps. I finally replaced the aftermarket thermostat with a new Toyota one and my temps in the winter ran a consistent 184. Now with summer temps & humidity in NC, it's running around 188 with high of 197 in stop & go traffic.

 

[2001LC]

FWIW:

I find it important to check under radiator cap, making sure coolant is to top of neck. This must be done two or three times, each time after an 8 hour cool down. Previous to this "check" run front and rear cabin heaters on full hot while engine at operating temp, making sure both blow very hot.

 

[94SRUNNER]

FWIW:

I find it important to check under radiator cap, making sure coolant is to top of neck. This must be done two or three times, each time after an 8 hour cool down. Previous to this "check" run front and rear cabin heaters on full hot while engine at operating temp, making sure both blow very hot.

This is a very sound tip.

 

[2001LC]

I think so! I get on my soapbox and beat the drum often in mud on this.

Proper care of coolant system is the most import PM we can do. It is right up their if not more important than lubes and filters. I'm seeing more and more blown engine due to coolant issues in our aging fleet. For the non-heavy duty wrencher, that's a ~$13K repair bill at a Toyota Dealer

I've developed a theory, that running coolant system just 1/2 inch or so low is causing premature heater tee and radiator top plastic failure. That air gap leaves plastic exposed to air, out of the coolant which has a plasticizer to keep plastic health. That the post 03 pink (Toyota SLL) aren't faring as well as systeming using Red (Toyota LL coolant) which are seeming to fairing better. This may be due to coolant itself, or more likely due to longer flush cycle of SLL which I don't advocate.

I use only Toyota products (coolant & parts) in coolant system period. I check coolant very often and recommend everyone do the same. The only exception is radiator.

 

[94SRUNNER]

@2001LC I too follow your logic. The importance of proper cooling system maintenance should be discussed and stressed as often as needed.

I have an update on my coolant system maintenance. My wife took it to work today. Approximately 70, mostly highway miles. She observed ScanGauge coolant temperatures between 188-190*. I am satisfied.

My next step is a new OEM radiator cap and coolant flush with Toyota Red over this weekend or next, followed by a new OEM fan clutch.

My radiator appears to be an OEM original. It has not discolored and Aside from the bent fins (which I will post up pictures of later) I think the radiator I in good condition.

 

[Spike555]

Yes cooling system health is vital.
I used to sell bulk automotive fluids and recycling services, including engine coolant. It's all the same stuff. Manufactures uses different coloring and stickers to scare you into going to the dealer.
Toyota Red is nothing more than red coolant, it is not a magic formula that prevent's premature cooling system failure.
Any aluminum safe coolant is fine.
When doing your once a week underhood fluids check look at the overflow bottle, is it full? Perfect. No need to remove radiator cap.
The cooling system "dumps" excess coolant into the overflow bottle as the coolant expands and then sucks it back out of the overflow bottle as the system cools, so as long as that bottle is full, you're fine. If that bottle is empty, then your cooling system might be low on coolant. If that bottle is full, your cooling system will be full.
I fill mine right to the top, let the excess spill out the overflow not he bottle and then the system levels out from there.

The best thing you can do for your cooling system is to change the coolant sooner rather than later, coolant is cheap, $8/gal for the 50/50 universal at your local store.
I do a drain and fill every 2 years no matter the miles. Because coolant is cheap. Even though it's long life, I change it anyway.
With the right testing strips you can check the condition0 of your coolant and know exactly how much life it has left, you check it like you're checking the ph balance of a swimming pool. Then you change it if needed, I do not have those strips, so I just drain and fill.

 

[Rolocado]

FWIW I just change my 217k radiator with an OEM. After markets might work just fine but peace of mind is priceless for me. 18 year life spans is something I can appreciate too.

 

[94SRUNNER]

@Rolocado I agree, the OEM may cost more but they tend to last the test of time.

 

[94SRUNNER]

Brief update...It got warm here (Dayton, OH) today and observed slight increases in coolant temperatures. Ambient was close to 90* with moderate humidity and all driving was in the city (lots of stop and go), never going over 45mph. Coolant temps ranged from 188-193* with a peak at 195* briefly at my forth red light in a row. Not to surprising given the driving and weather conditions and the fact that I believe my fan clutch is a bit on the weak side and the coolant is old.

 

[Spike555]

Brief update...It got warm here (Dayton, OH) today and observed slight increases in coolant temperatures. Ambient was close to 90* with moderate humidity and all driving was in the city (lots of stop and go), never going over 45mph. Coolant temps ranged from 188-193* with a peak at 195* briefly at my forth red light in a row. Not to surprising given the driving and weather conditions and the fact that I believe my fan clutch is a bit on the weak side and the coolant is old.

Humidity has zero to do with engine temp.
Fan clutch has everything to do with engine temp.
Coolant lasts forever, it is the corrosion and lubrication additives that go bad. The freeze/boil part of the coolant never ever goes bad.
Coolant can be recycled and made new again.

Motor oil is the exact same way, it never goes bad, it is the additives that go bad and contamination that make motor oil changes needed. But that oil can be recycled back into brand new.

 

[94SRUNNER]

I wanted to follow up as I have finished with my coolant system refresh.

This past weekend I replaced the fan clutch of a new OEM unit and drained the old coolant. Additionally, while inspecting the radiator, I noticed that a large portion of the front side of the radiator had a large area that appeared to be blocked by dirt and debris, so that was cleaned up. Over the last 4 days I have flushed the system 5 times using distilled water. Last evening I filled the system with 50/50 mix of Toyota Red and distilled water.

Previously I have replaced the heater tees and thermostat (as mention above).

For now, the system is in good shape. Coolant temperatures range between 186-193* depending on the typical variables such as ambient temps, whether or not I have the AC or heat on, and grade of the road. While pulling long hills and in stop and go traffic with the AC running the coolant temps occasionally hit 195*.

In the near future I plan to replace the radiator. I have about 20K until the timing belt needs to be done according to the service calendar.

I'll use this thread to continue to document my cooling system performance and maintenance.

 

[Spike555]

As part of my spring/fall cleaning I rinse the engine, engine bay and radiator fins with the garden hose.
Pollen will collect on the fins and reduce cooling but you cannot see the pollen.

 

[94SRUNNER]

Mid-trip update...

Drove to Destin, FL with the family and loaded down 100. Rig ran great, even with upper 80’s and 90’s. Coolant temps ranged from 186-193*, and sometimes hitting 195 cresting hills.

The only issue I had was on the drive from Gulf Breeze to Destin we hit some horrible traffic was standstill to a slow crawl for a good portion. Ambient temperature was mid 90’s with a heat index of 114. Observed Coolant temps during the stop and go traffic were 197-207 (transmission in D) AC stay cold. Temps dropped once the truck resumed moving. I’m thinking the high ambient temperature and stagnant air were not helping matters. Before we reached our destination, we had to make a stop to pick up something. I parked, left the truck running with the AC on, and went in for about 10 minutes. When I came back out coolant temps were 191*. I had several other instances on the drive where we stopped on the interstate for construction or and accident and the coolant temps never broke 193*.

I’m thinking the aftermarket Asian Fan clutch may be out of spec, as I wasn’t hearing the roar of the fan clutch fully engaging.

Otherwise just enjoying this refreshed coolant system.

 

[Spike555]

Dude. You're fine. You are chasing unicorns and rainbows.