A Fluctuating Engine Temperature? A quick fix.

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PopRivet

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Acrtic
Hi. Having just finished my High Pressure Injector Pump overhaul (seals), and not replacing the coolant pump, I carried out some research as to why my Engine Temp fluctuates quite wildly.
Living in a mountainous region, I've noticed the engine temp (ET) fluctuates, and can get quite cool as I tend to freewheel into my local village. It's a steepish road with lots of bends, and gravity does most of the work.
Climbing home again and the ET goes up. Hmmm, I did wonder if the coolant pump may have been suspect, especially as there was a sound like a washing machine at times beneath the bonnet.
However, my testing of the coolant pump while the drive-belt was removed persuaded me the pump was okay. Therefore, it must be the thermostat instead. And even though I have a new one to fit the job can be laborious and time consuming. I'll wait unti I really do need to replace the pump, or perhaps the suspect thermostat, if required.
My research indicated there is a common fault with the Freelander 1 Thermostat sticking open, whereby the engine has trouble reaching its required operating temperature.
Then the discovery was found; and I'm sure that what I'm about to disclose will be known by many already, although perhaps not condoned as a long-term remedy - by any means. I, however, am about to carry out what I have learned.
The upper-hose on the heating/cooling system, between the radiator and the engine, can be used to house a seperate thermostat, one that will operate and control the ET even though there is another in use. It's quite simple, really. The stuck-open thermostat allows water to freely circulate around the engine, cooling it to a temperature that is below its preferred working temp. This in turn means the engine may not be as economical or efficient as it should be. The added thermostat should effectively control the ET to the point where the engine operates better.
The thermostat is placed into the upper radiator hose, which is 22mm in diameter. It fits into the hose perfectly and will not damage the engine or anything else. I'm attaching a picture of what I've ordered from Ebay, so you can see what is required. The thermostat is pushed into the engine-end of the hose, with the brass part facing the engine. It's a quick job and should be most efficient. The Rover 75 has the same problem as the Freelander, as it uses the same engine, and many owners have already used this quick-fix, successfully. I dare say, many Freelander owners have done so too.
The Thermostat is for a Renault 5, and other models too. Imagine the Frogs buuilding something that is so simple and extremely efficient? Incerdible! Especially when it was they who built the unbelievable Maginot Line. lol Still, never too late, I suppose.
The thermostat I bought and intend to fit is rated at 83 degrees for opening. The Freelander thermostat is rated at 82 degrees. Close enough. But be careful, because the Renault thermostats come in several differently rated temperatures.
Here's the one I've bought...
Thermostat Renault 5 9 11 19 Rapid 1.0i 1.1i 1.4i New 7700575874 7701348376
£8.79 sold by sm.autoparts (Ebay handle).
RENAULT 5 THERMOSTAT for TD4 Mod.jpg I hope this helps anyone with a similar or same problem.
 
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I only ever use the gates thermostat as some of the other stats have a bleed hole or weep hole, so take longer to reach temp, gates reaches temp quicker in my opinion and opens at 88c if I could have found one at 92c that would have been fitted
 

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Hi Arctic, I take on board what you write, but also take note of the original designed running temp. I considered an 89degs thermostat, but opted for the lesser and more closer to the BMW engine requirement. The hotter an engine, the thinner the oil & its protection. Also, as more heat creates higher pressures, leaks and fatigue in the components & their fabrics can occur earlier than anticipated or predicted. I prefer the Cooler option & better protection. And for Spanish summer temp's, I choose a thicker oil. But for more northern climates, an 89deg thermostat would probblybe the wisest choice. For me, in sunny Spain, an 82 does it.
 
I actually drilled a 1.5mm hole in my in line stat. I did this to improve the bleeding of the system. In retrospect, I have probably just slowed the warm up time, which is about 4 miles.
 
I used a QH thermostat for the same trick but would not recommend it. The edges of the fat end are not rounded off like on the Gates so it was a right mare to fit in the pipe.
 
I used a QH thermostat for the same trick but would not recommend it. The edges of the fat end are not rounded off like on the Gates so it was a right mare to fit in the pipe.
Thanks, Alibro, for the info. I'll check what arrives and go accordingly. Your warning is well received.
 
Thanks, Alibro, for the info. I'll check what arrives and go accordingly. Your warning is well received.
NP mate, TBH if you find the one you get is not rounded off nicely like the Gates it would probably make more sense to order again as they're so cheap.
 
NP mate, TBH if you find the one you get is not rounded off nicely like the Gates it would probably make more sense to order again as they're so cheap.
Roger that! I'll do exactly as you suggest because it makes a whole lot of sense. Thanks for that. And hope anyone else who is experiencing the same takes heed of your advice.
 
Roger that! I'll do exactly as you suggest because it makes a whole lot of sense. Thanks for that. And hope anyone else who is experiencing the same takes heed of your advice.
Plenty of lube and a short pipe the right size for pushing it into the hose, otherwise you can easily damage the thermostat.
A grinder or dremel is handy for cutting the hose clamp then a new hose clamp the right size for putting it back together.
I normally remove the manifold to do it and cut the hose clamp in situ but you might have more luck than I have disconnecting the hose.
 
First proper cold morning start for me this winter. Happened to notice my TD4 slower than ever to get up to temp. As a result, I'm considering this mod. Is it good for the long term or is it worth stumping up the cash for the garage to do my thermostat (and probably a pump since they'll be taking that off anyway)? I'm due a coolant change so seems as good a time as any.
 
First proper cold morning start for me this winter. Happened to notice my TD4 slower than ever to get up to temp. As a result, I'm considering this mod. Is it good for the long term or is it worth stumping up the cash for the garage to do my thermostat (and probably a pump since they'll be taking that off anyway)? I'm due a coolant change so seems as good a time as any.
I can't see any point in chucking a heap of money at it when a tenner will sort it.
 
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