Cooling Issue Still 225 engine.

[Matt Cole]

I posted on here a while back about the cooling system issues im having with the 225 engine and its still going on. With the standard 89 deg stat in, the temp rises to 100 deg (temp took from back of thermostat housing mechanical gauge) and then rapidly drops to say 85 deg. It then repeats the cycle in quick succession. I drilled a 4mm hole in a spare stat and that improved things (bit better regulation) but regulation was still an issue and 90-95 deg on the gauge most of the time. What is strange is that on decelaration in a low gear the temp drops to around 80 deg quite quickly. I have an adjutable fan switch which makes no difference as when its on the temp still rises. It might go off now and again when the water after the stat cools a little. I have tried plenty of stats and they all do the same. The pipework seems to make sense how its piped up. Its a regulation /flow issue i think. Im needing to sort this out before driving the car anymore. Any ideas chaps??

[Schakal]

you aure there is not an airlock or even a faulty sensor or gauge ?

[Ashy]

the 172 thermostat was no better then matt? Might be worth sorting the coolant leak?

[JRP]

I seem to remember reading about this.. somthing about a gasket that the stat sits in becoming dislodged causing a flow restriction.

If your talking about what i think you are. if not ile get my coat

[Matt Cole]

I seem to remember reading about this.. somthing about a gasket that the stat sits in becoming dislodged causing a flow restriction.

If your talking about what i think you are. if not ile get my coat

Ive got the hat to go with your coat chief!

[Matt Cole]

the 172 thermostat was no better then matt? Might be worth sorting the coolant leak?

Worse mate. With the drilled stat 95 tops but would hover below that. With what we did today its doing the '100 to 85 move'! and then back again. Not convinced on the leak being the culprit but yeah it needs sorting.

[Matt Cole]

I think im looking at replacing all the hoses so the standard restrictors will be gone!!

[Duncan Grier]

Water pump in good condition? No blocks in the system inc rad? Sound like when you are using the rad to cool it works but it is getting it through the rad?

Could be wrong have been, just a few time before lol

[Adey aka Ewok]

whats the running temp ment to be?

[Duncan Grier]

One for PAul B to prob answer Adey - suspect 90deg could be normal

[Adey aka Ewok]

Just thinking it might be a warm running engine that's trying to be over cooled, valvers run hot, the statvon them isn't fully open until 101degs

[Ashy]

the standard 172 stat i 89 degs, nt sure what the 225 is as standard though?

[THE MASTER]

get a torch and shine it through the rad . have a look on the other side of the rad and see how mutch grunge / dead flys etc are blocking the air flow

[Matt Cole]

The rad is pretty clear and it does cool once the stat opens and lets the cooled water circulate around. The stat at that point must shut quite quickly and the temp rises to 100 deg again. The original stat is 89deg or at least that was what was in it. It does seem like the rad overcools the water to below 89deg and the stat shuts quickly. Im using a 172 rad.

[Matt Cole]

Im not sure if it is the water pump as the water must circulate when the stat opens and cools to 85deg. Its like there is a lack of flow around the engine and its not being regulated by the stat to keep the temp at around 89deg?

[Duncan Grier]

Is there any difference (much) to the std 225 coolant pipe / rad setup?

[Matt Cole]

not sure how the 225 is piped up. I dont think there is any installation diagrams available.

[Andrew Cooke]

I don't suppose it'll be much different to this

[Andrew Cooke]

actually, this might be better

[Matt Cole]

Thanks Andy. I worked that out to be correct looking at Ashy's spare 172 engine. The thing is on the 225 outlet/bleed no.6 is blocked off. I'm also unsure on where to pipe up the turbo within that circuit.

[Belly]

New poster! (less than 10 posts)

Hi i dont know nothing about these engines at all so just a suggestion what are the water pumps like on these? are they a plastic impeller on a metal shaft? basically one of my transits did something similar it turned out to be the impeller slipping on the shaft, it would get quite hot then cool rapidly then hot again the pump wasnt producing enough flow engine got hot stat open and all the cold stuff would mix shut the stat and get too hot again as well as lots of other strange symptoms, sometimes mostly whilst trying to get it diagnosed the van would be ok so the impeller must have gripped sometimes and slipped others etc! as i say i dont know nuffin about them just a thought

[Mr 5]

New poster! (less than 10 posts)

Hi i dont know nothing about these engines at all so just a suggestion what are the water pumps like on these? are they a plastic impeller on a metal shaft? basically one of my transits did something similar it turned out to be the impeller slipping on the shaft, it would get quite hot then cool rapidly then hot again the pump wasnt producing enough flow engine got hot stat open and all the cold stuff would mix shut the stat and get too hot again as well as lots of other strange symptoms, sometimes mostly whilst trying to get it diagnosed the van would be ok so the impeller must have gripped sometimes and slipped others etc! as i say i dont know nuffin about them just a thought

great about to say that! realy common fault on VW,intermitent temp issues caused by the plastic impeller on the water pump,not sure if modern renault engines have plastic impelers on asswel?

worth a investigation i guess

[Matt Cole]

Well it would make sense to investigate the pump all the same. Shame its driven from the cambelt ! Can anyone offer a dialogies diagram of said part so i can have a look at the component breakdown? If its not too expensive or a chew on i may try and change it.

[stuTHC]

Well it would make sense to investigate the pump all the same. Shame its driven from the cambelt ! Can anyone offer a dialogies diagram of said part so i can have a look at the component breakdown? If its not too expensive or a chew on i may try and change it.

Id be sorting that coolant leak that ashy mentioned before ripping the water pump apart Matt. When i first got my 5 the temp used to be up and down just like you say. Tried everything i could think of at the time, new stat, rad, water pump............it wasn't until i was shown how to make the old coolant bottle top/tyre valve gizmo that i could pressurise the system and discovered a pin hole leak from one of my hoses (on the heater matrix). Sorted the leak and temp problem went away.

[Matt Cole]

Right chaps i have piped up the cooling system as shown here:

https://www.rtoc.org/boards/attachmen...5&d=1241638861

I have put the turbo inline on the heater matrix return. I have no restricters in place. Any comments on issues with doing so?

[Matt Cole]

bump

[i l k e r]

I have put the turbo inline on the heater matrix return. I have no restricters in place. Any comments on issues with doing so?

Matt, water that goes through the heather matrix is quite hot, do you think it will do a good job of cooling the turbo?

[Matt Cole]

Matt, water that goes through the heather matrix is quite hot, do you think it will do a good job of cooling the turbo?

I would have thought that the temp would be around 89 deg at any point in the system?

[Ashy]

be hotter than that after the blower marrow!

[Matt Cole]

You know when i have looked at it again, i would be pumping hotter water back into the coldest part of the system?

I really need to see how the 225's are piped up and sort this once and for all!

[Ashy]

You know when i have looked at it again, i would be pumping hotter water back into the coldest part of the system?!

Yeah but in terms of volume its gona be feck all... doubt it would make much difference?

Worth a try surely.

[Matt Cole]

i suppose so matey. Would be nice to know for sure though before it all goes back together.

[stu21t]

what about the coolant bottle cap?
check its releasing at the correct pressure.
i had loads of grief on my birds bm,turned out it was the bloody cap not holding pressure.

[Matt Cole]

what about the coolant bottle cap?
check its releasing at the correct pressure.
i had loads of grief on my birds bm,turned out it was the bloody cap not holding pressure.

Good point, i was using the gt cap and bottle. However, ive got a bottle and cap of another megane. Blue cap bottle with only one feed.

[stu21t]

on the cos theres only 1 bottle outlet like in the diagrams posted above
then it Ts into the bottom rad hose.
and the turbo return hose drops straight into the top of the expansion bottle

and surely the water coming out the heater matrix is cool as its like a rad?

[Matt Cole]

Stu, can you knock up a quick diagram? Maybe on the attached pdf??

[paul b]

Matt....temp on stat is correct and I agree that it sounds like a flow issue....

pop up some pic's and let us have a peep in case we (royal we) spot something...

also, have you had the water pump off,,,,,without knowing the history of the engine it may be as simple as a water impeller fell off....
also seen the auxillary drive belt on the wrong way so it ran a water pump backwards...easy stuff to miss,more so if the engine turned up in bits.....


also, basic rule of thumb without seeing your pipe work...water pump hose to top of rad....stat to bottom hose on rad..

[Matt Cole]

Matt....temp on stat is correct and I agree that it sounds like a flow issue....

pop up some pic's and let us have a peep in case we (royal we) spot something...

also, have you had the water pump off,,,,,without knowing the history of the engine it may be as simple as a water impeller fell off....
also seen the auxillary drive belt on the wrong way so it ran a water pump backwards...easy stuff to miss,more so if the engine turned up in bits.....


also, basic rule of thumb without seeing your pipe work...water pump hose to top of rad....stat to bottom hose on rad..

Paul, (saviour) is there any diolagies of the pipe set up?? Been looking for info but had little or no joy. I havent checked the pump (stupid yes) Im hoping its just the setup.

[paul b]

yup, i'll dig em out after lunch.....also, is yours an R26 or the F1 lump with LSD...just so i put the right info up..

[Matt Cole]

yup, i'll dig em out after lunch.....also, is yours an R26 or the F1 lump with LSD...just so i put the right info up..

Just the normal 225 matey 2004/05 i think. I bet the engines are the same??

[paul b]

[paul b]

all the pics so far for megane turbo in here..

http://s88.photobucket.com/albums/k1...ogys%20megane/

[Matt Cole]

Paul, massive thanks.

Ok its not a clear circuit so i need to i.d the pipes for my set up. Which ones are the heater matrix flow and return, the turbo flow and return? I presume the fill tank is at the top left in the pic?

Paul i know its a tall ask but have your chaps got that section in the workshop manual ala the clio 172 one that Andy Cooke supplied in the PDF attachment? It would be very easy to follow the pipe routes then. (pint will be awarded)

[paul b]

sorry buddy, all that dialogys is on a stand alone Mac.....not linked to email or our internal internet......

the pics I put up are from the renaultparts system, online dialogys for parts only..


pipe 15 is top matrix, pipe 3 is lower matrix
header tank is top left....

guessing pipe 7 is the turbo side of cooling......don't have a car here to look at, sorry..

[Matt Cole]

Ok matey, so need to id pipe 4 and where the first pipe of no. 2 goes to?

Apologies for all the questions.

[Woznaldo]

great about to say that! realy common fault on VW,intermitent temp issues caused by the plastic impeller on the water pump,not sure if modern renault engines have plastic impelers on asswel?

worth a investigation i guess

Ditto on the pump. Missus had a '96 1.4 Polo CL that had some bizarre temp readings and it turned out to be the impeller on the pump had detached! This pump was also driven by the cambelt.

[Duncan Grier]

An option could be to ditch the stock setup and run an external water pump (like an EWP)

Hope you can track it down though

DG

[Matt Cole]

Update:

Right chaps i have had a good few issues recently which all but one remain! The cooling system is still playing up even after re-routing and re-piping it all as per the previous posts. The leaks seem to be cured and all seems well. The temp is still irratic climbs up to 100 deg, then rapidly drops to about 89 ish, then rapidly climbs back up. Sometimes it hovers around 90 deg whilst driving, but generally its as the cycle described above. Im not sure if its the pump? If the pump wasn't working i presume it would just overheat end of? I have the fan set at 90deg to come on which it does as soon as the stat opens up. Sometimes it goes off, other times it stays on for a couple of cycles. There is cooling happening but no stability or regulation even when driving.

Help

[stu21t]

are you running a std pully set?
maybe the waterpumps spinning too quickly and bubbling up the water?
might need to slow down the pump with a diff pulley,
if they are all std then ignore me lol

[Matt Cole]

Update, i have drilled two holes in the stat and banged that in with the revised cooling pipework system. It now stays at around 75deg which maybe a little cool but on a good rag it sits at 82deg ish. Fan comes on at 92 and goes off at 80 odd. Much happier and its not as hot in the engine bay when i was seeing 100 deg temps!! I still dont know what the issue is but at least its stable!