Great thank you. I think I will go the route of new 180 oem tstat and all new hoses aka stock system when that time comes, but I appreciate the creativity. As long as my realtime monitoring with software to obd2 is available I'll be able to detect any changes in performance and temps.

"Chance favors the prepared mind" ML Cimo

 

Wow no offense but the "greatest safety reliability mod" also seems to be one of the most stupid and dangerous mods in my mind.

If you take the time to study the cooling system you'll appreciate that the entire system was designed around the bypass idea and that you can't just hack stuff off and block other things or tee them off.

Most of the inline mods are reliant on the heater core "bypass" loop taking up ALL the coolant flow slack when the inline thermostat is closed fully, ie when the engine is cold.

If you've got an older system (heater core etc) and you've gotta merge through an onramp with a cold engine and you hit redline please let me know how long this system lasts before you blow a hole through your heater core.

Even the RAVE manual states the reason behind the idle bypass spring is to reduce coolant pressures through the heater core loop when the thermostat is closed.

Anything above a high idle and the spring opens to reduce pressure on heater core loop.

...so what do we do? Remove bypass and ensure that 100% of available pressure and flow is forced into that exact same loop? In vehicles that are now ~15 years old no less. Perfect. This is the "mod of the year"..

The correct course of action (unless you're an engineer or something, then feel free to call me out) would be to identify the weak links in the OE system and fix everything / bring it back to OE standards.

I've replaced the thermostat with OE twice on this vehicle - once out of concern due to aux fan turning on and high idle temps - the second time due to a collision. BOTH TIMES two of the four "sensing holes" in the thermostat were blocked by crap. That's 50% of the sensing area of the thermostat. In a bypassed state the thermostat NEEDS these holes open and free in order to send coolant through the radiator and detect increases in engine temperature before it's able to open. Because it's based on a percentage, if the holes are blocked the thermostat opens later, this is why many people have high idle temps and aux fans turning on. Especially in the winter (yeah, doesn't make sense right?) when the coolant flow through the radiator is so reduced that by the time it hits the sensing area of the tstat it's COLD and it closes the tstat even more, increase temps more! Rave even mentions this phenomenon in extreme climates and in winter as being normal which is fine BUT if you've got blocked sensing holes it will become potentially dangerous as the thermostat is basically sealed shut. The exact same concept applies to normal climates if you cut the flow in half with blocked sensing holes and give the coolant twice as long to cool off in the radiator before it hits the tstat.

The #1 reason for the motorrad tstat IMHO is the two LARGE sensing holes instead of 4 small ones. The objects that blocked the OE units would easily pass through the two larger ones in the motorrad unit.

Guess what? I have normal idle temps and my aux fan has never turned on again.... not in 5 degree winter temps or 80 degree spring temps in traffic.

This is the "real" solution to the problem as it maintains the original design but fixes the flaw.

 

I have to say I knew this comment was coming, so no offense taken. Also I'm only a junior level mechanical engineering student(not a 4.0 student), so I'm not gonna claim I have all the engineering knowledge to call you out on anything.

I don't have an older cooling system. I replaced both my radiator and heater core about 3 years ago. I also haven't spent much time studying the oem cooling system I just knew I went through SEVERAL failing motorads in a short period of time and wanted to try something else. I'm not gonna say the original engineers that designed the Discovery were right or wrong, just that sometimes a budget is reached and you have to go with what you decide is the best at the time.

No offense to you, but your example of redlining on an onramp with a cold motor "seems to be one of the most stupid" situations ever in my mind. I feel that if you were to do that with an oem setup you're still asking for trouble. I've never needed to go over 3500rpms though so I have no redline experience with that situation on a motor up to temp either.

On to comparing thermostats. I travel a lot and had 4k miles over the life of 4 motorads and 1 OE. I have gotten 20k miles out of 2 Chevy 180* inline thermostats. I understand the need for the holes which is why my inline has a 1/8in hole drilled in the top.

I have had the multiple holes blocked in the OE style thermostats but never have I had my single hole blocked in my inline. Why is that? Some at first may say luck, or you could say the OE style caught all the loose trash in my system. Upon inspecting each blocked OE style thermostat I realized it was seals from the thermostat itself blocking the holes. The seal in my inline housing is still in perfect shape and in one piece and hence my single hole is working just fine. So say we have both styles in perfect working condition which thermostat is closer to the motor to sense the temperature? I could be wrong but I'm pretty sure it's the inline.

The #1 reason for the inline mod in my opinion is with my personal experience it has been more affordable and has given me more consistent temps.

I have a 180* idle temp in 20 degree winter temps and 100+ degree summer temps in traffic. My aux fan only comes on with AC, if yours isn't coming on ever you may need to check that out.

The "real" solution in my opinion even though I'm pro-inline is for people to do whatever they feel more comfortable doing.

BTW I still have a motorad on my 99 because it's only driven about 30miles a week, but do I truly trust it.....not a bit.

 

As an engineering student of any kind at any level I feel like you'd have to call into question the possibility of ~7 different thermostats failing on you in what.. 3 years? Including multiple OE units designed to last 75k+ miles?

There's definitely something else going on here.. I understand what you mean about reaching a certain budget (I keep that in mind every time I turn the key - as these things aren't exactly worth a whole lot…) but at the same time, the original system was designed to offer superior performance when maintained correctly, it just so turns out that adding 3x the parts to a cooling system creates more problems than it solves thus we see LR and other companies ditch the system after one round. The issue of increased temperatures at colder ambient temperatures is one which will always plague the system though, unless it's running at 110% OE showroom condition (ie. none of the 4 sensing holes plugged) which is unrealistic for any vehicle, much less a Land Rover.

My example of redlining on an onramp with a cold motor isn't a stupid situation at all.. It's just being defensive from an engineering point of view (I've certainly never done it).. and I respect your ideas about babying the motor but you should know I take it to a whole other level and haven't seen over 2500 RPM in over a year probably… HOWEVER when I work on my vehicle (and for you.. as a prospective engineer) I always consider the worst case scenario, which on a vehicle usually involves the idiots around you more so than just yourself. There are situations where you might need the full power of a vehicle, even when it's cold… even when it isn't ideal… I don't care if there's a tornado behind you or someone chasing you with a gun in a parking lot. I'd rather not blow a LOW pressure hose in the process - 1/8" hole or not.. if your tstat is closed it's the ONLY PATH for your coolant!! Period!! (Specifically why the OE system has a bypass spring / loop in the first place for any RPM above idle!)

The need for the holes is entirely different on the OE system vs. your inline system. When the bypass OE system is cold (and at idle, ie bypass spring closed) the entire radiator and thermostat loop becomes STATIC. It stops. Entirely. This is great since you get cabin heat almost instantly.. (the only flow path remaining) unfortunately that closed loop increases temperatures so quickly that the hot water has a difficult time getting to the thermostat and opening it. The TINY thermostat holes are the only thing which allows the flow to continue at all. Even then, with the remote thermostat.. the holes only allow water to leave the radiator.. then new (hot) water to enter radiator THEN true engine temp water to travel over the thermostat. It's not like an engine-mounted tstat which sees engine temp immediately. This slowed / idle bypassed path through radiator is why RAVE manual mentions significant idle temperature increases in harsh climates, due to cold water closing tstat even more).

It's not a coincidence that the motorrad unit has two larger holes instead of 4x smaller ones… they figured all of this out (2x less likely to get debris stuck in there).

In your case I guess a 1/8" hole would relieve some pressure w/ an inline setup, but it's still not how the system was designed, and if the thermostat is in the process of cycling closed and you pull out of a parking lot or whatever from idle you'll still put a pressure surge through the heater core loop.

ANYWAYS. SEVEN THERMOSTATS!?!?!?!?!

I have a 16 year old 1999 DII with 175k miles on it and have only replaced the thermostat twice.. once because I was redoing the entire cooling system (hoses, tee section update, waterpump, etc due to collision) the other early on was because of high idle temps, which proved to be clogged sensing hole / dex crap coolant. I've NEVER had one fail, knock on wood. Things seem MUCH better after flushing to regular generic green coolant.

Even for you to somehow defend your mod by saying you've only used two chevy stats over 20k miles is absurd. You're talking about a 100,000 MILE THERMOSTAT lasting 10k miles and acting like that's good? As I stated above, you've got something else going on…. not that I'm aware of anything that would cause ANY thermostat to fail so quickly (LR, ebay, or otherwise) but wow. what you're saying is just statistically almost impossible.

I have no idea what you're talking about saying the OE "seal" is blocking the thermostat holes but again, sounds like something is going wrong.. you have to remember the hundreds of thousands of these vehicles made.. and while they are famous for unreliability, it's not like they were blowing up after a few months from the showrooms due to thermostat failures, this took almost a decade of crap and 20 degree increases in idle temps ONLY to cause people concern, plus possibly the inherent fatigue associated with temp flux and gasket failure leading to other problems. You blowing through 4 motorrads, an oe and 2 chevy stats in a couple years is absurd.

As far as affordability justifying your cause goes - I've purchased one motorrad on a 16 year old vehicle versus you buying 7 of various types plus your mod expenses, coolant each swap etc.. hmmmm. Oh plus I still have almost instant heat in the winter and a warm engine which was LR's entire point of this mess lol!

I'm saving some miles on the LR3 the past couple weeks for an upcoming road trip and have been enjoying the 99 DII about 35 miles a day in severe stop/go traffic since she's been sitting over most of the winter and I couldn't be more happy, makes me want another one (oh God no… )

PS my aux fan comment was directed at my pre-coolant system overhaul / pre-motorrad, when I'd have the aux fan turn on in the dead of winter at idle (clogged hole, reduced flow and temp over tstat causing it to close and increase temps). I have since installed a 16" e fan after going through two seized OE aux fans (one original, the other off a parts car which was probably almost same age..) which works great with the AC and cycles normally based on ambient temp and vehicle speed as spec'd. Never activated due to coolant temp / high idle temp again. *knocks on wood*

 

Honestly man we are going to continue to see things different regardless and that's ok. I just have to add that when I was getting my motorad thermostats it was pretty widely known at that point in time that a lot of people were having issues with them. They went through a period that quality control was aweful. For me they either wouldn't open or the seals inside would fall apart. As for the 2 Chevy thermostats I technically haven't ever had one fail. I tried my first one with 2 holes and I didn't like the amount of temp swing so I added one with one hole instead and it's worked great for me.

 

I don't know about all that... I'm doing the inline mod because it looks cool.

 

Seems legit. I'm down. With some further modification of course.