14 replies to this topic

[AndrewUK1990]

hi everyone, i have a problem with my mini in that it always runs cool. It is an MG metro engine unleaded head version. i have an 88 thermostat fitted and ive drilled 3 small holes around its circumfrance as i do not have a bypass hose. I have drilled out the heater take off on the end of the head too which is connected to my heater with no shut off valve so it runs through it constantly. I also have a 4 core radiator fitted.

ive checked my temp guage and it works properly but it says engine runs cold, the needle points just at the top of the blue bar. I did briefly run the engine with a thermostat without holes in and it made no real difference in temps so i dont think thats the problem.

Now also ive run this engine before on a 2 core rad and at the time it didnt have the heater takeoff drilled out on the head. i also had the heater piped up from the metro thermostat housing as a bypass link. back then it ran at perfect temperature all the time.

is my engine running cold because of the heater take off or something? its confusing me, only thing ive not tried is to use a new thermostat but ive tested it in boiling water and it works properly as far as i can tell.

any help would be much appreciated! sorry for the long post

[liirge]

Well, hooking up the heater permanently means you are essentially running coolant through a small radiator all the time! not surprise. What i would do is keep your current set-up and NOT drill the thermostat, you should then see it move.

Also is your water temperature gauge electrical or capillary?

[mike.]

I don't think having the heater plumbed in will cool the engine much unless you've got the heater fan on and the windows open all the time; the hot coolant going through the heater won't cool much if the fans not on to push air through the matrix. My engine ran warm all year round with the heater tap open.

What sort of fan do you have fitted? If you've got a hot climate fan fitted it'll cool the engine much more than necessary for UK climates.

Also what size holes have you drilled in the thermostat? They only need to be maybe 4-5mm. I wouldn't suggest not having holes in the thermostat though, that'll give you no coolant flow at all until the stat opens.

Edited by mike., 30 April 2011 - 05:25 PM.

[AndrewUK1990]

Well, hooking up the heater permanently means you are essentially running coolant through a small radiator all the time! not surprise. What i would do is keep your current set-up and NOT drill the thermostat, you should then see it move.

Also is your water temperature gauge electrical or capillary?

Cheers for the help. My temp sensor is electrical. Now thing is I can't get rid of holes in thermostat because MG engine is blanked off for the bypass hose. Also i cant pipe it up so that my heater comes off the thermostat lid and acts as a bypass anymore because i have a top engine steady there which unfortunatly means the metro thermostat cover wont fit!

but i could try maby putting a heater valve on the take off on the head and see if the temp goes up with it closed off.

by the way soz for bad english, ive typed all this on my mobile!

Edited by AndrewUK1990, 30 April 2011 - 05:30 PM.

[AndrewUK1990]

I don't think having the heater plumbed in will cool the engine much unless you've got the heater fan on and the windows open all the time; the hot coolant going through the heater won't cool much if the fans not on to push air through the matrix. My engine ran warm all year round with the heater tap open.

What sort of fan do you have fitted? If you've got a hot climate fan fitted it'll cool the engine much more than necessary for UK climates.

Also what size holes have you drilled in the thermostat? They only need to be maybe 4-5mm. I wouldn't suggest not having holes in the thermostat though, that'll give you no coolant flow at all until the stat opens.

thanks m8, the fan is one with lots of small blades and it does seem to push a lot of air! also like i said i have a 4 core radiator. The holes in my thermostat are only small, just 3 holes of 4mm. also like i said b4 ive tried it without holes jst out of curiosity and it made almost no difference in temperature, jst slightly lengthened the time to warm up. Im thinking if i put a heater valve in and shut it off that might help a bit. otherwise ill try swap the fan for one with less airflow.

[mike.]

The standard fan is the plastic fan with 11 blades, if thats the one you've got it shouldn't be over cooling. Also like I said, I used to have my heater valve open all the time as my heater tap was jammed open and my car always ran at the right temp. The heater will do very little to the cooling unless theres air going through it when the heater fan is on.

I'd say you temp sensor is playing up to be honest - If you take the car for a run how hot does the engine bay get? - All over the engine bay should be very warm and hot to the touch really.

[AndrewUK1990]

The standard fan is the plastic fan with 11 blades, if thats the one you've got it shouldn't be over cooling. Also like I said, I used to have my heater valve open all the time as my heater tap was jammed open and my car always ran at the right temp. The heater will do very little to the cooling unless theres air going through it when the heater fan is on.

I'd say you temp sensor is playing up to be honest - If you take the car for a run how hot does the engine bay get? - All over the engine bay should be very warm and hot to the touch really.

i replaced the sensor a few days ago, both give me same results :/ but i know the engine must be close to the correct temps because it is hot to touch, the radiator included. Thanks for the info about the fan by the way, no need to swap that then. I'll try the heater valve thing just because its pretty easy to try and low cost so may as well, even though i doubt its that as you have pointed out. If that doesnt work ill just leave it i guess, cant see any other real reason why it would actually be running cool.

it will be going for rolling road soon anyway so maby ill see if they hav any ideas what it could be.

[AndrewUK1990]

Hello again all, well I've replaced the thermostat with a brand new 88c one and not drilled any holes in it as i have the heater take off (on left side of head as looking into engine bay) drilled out and attached so that it works as a permanent bypass. The engine now appears to run well and gets hot to the touch, the heater even works very well and seems very warm. However, the temp gauge still only goes just above the blue line and will only start creeping towards the center line if stuck in traffic for more than 5 mins. As i have said before i have replaced the sender and it is the correct type. Also the gauge does hit max if i short it out on the engine block so i know thats working fine.

I really cant think of what could be causing the gauge to read where it does, other than the fact i have a 4 core radiator. However, am i right in thinking that surely if the thermostat is brand new and only opens at 88c which it does as i have tested it, then the engine must run at 88c because water cannot flow into the radiator before this temp is reached..?

Any advice or suggestions as to what this might be would be greatly appreciated. Many thanks!

Pic of my engine bay and pipework:

Edited by AndrewUK1990, 05 May 2011 - 04:03 PM.

[liirge]

Is the Radiator and top hose really warm to touch after a run?

[AndrewUK1990]

Is the Radiator and top hose really warm to touch after a run?

yes the radiator, hose and thermostat housing get hot after a good run - enough so that you cant touch the housing for too long or it would be painful! The internal heater also blows hot air. I think its probably running about 88c or there abouts, but i just don't understand why the gauge doesn't move further up than the blue mark. As i said, only in traffic on a hot day will it start to creep up towards the middle mark.

by the way i have fitted a 998cc housing on top of the MG metro head so that i could fit the engine steady i had over the thermostat housing. I take it this wont cause any problems as to sealing the hole around the thermostat will it..?

Edited by AndrewUK1990, 05 May 2011 - 06:19 PM.

[mike.]

Its got to be a problem with the gauge then, if your heaters getting hot and blowing warm it sounds fine.

Maybe its a problem with the voltage stabiliser, I'm not too sure how they work but have a look at this thread: http://www.theminifo...howtopic=146527

If those are the clocks you've got fitted that might be your solution.

[bmcecosse]

It must be the gauge - ONE hole X 1/8" in the stat rim is sufficient.

[AndrewUK1990]

Its got to be a problem with the gauge then, if your heaters getting hot and blowing warm it sounds fine.

Maybe its a problem with the voltage stabiliser, I'm not too sure how they work but have a look at this thread: http://www.theminifo...howtopic=146527

If those are the clocks you've got fitted that might be your solution.

Thank-you for the link! That actually seems like this might be my problem! I have those exact dials, but i don't have a voltage stabilizer fitted. I am sure the engine is running at correct temps now anyway, i did a check with a thermometer in the rad and it went to about 85c so im guessing it will be at least 88c where the thermostat is or else it wouldn't open and let the rad get hot.

Well ill fit this to my gauges in a couple of weeks because im busy right now with uni exams. Ill post up the result when ive done it.

Thanks all for the help, very much appreciated!!

[998dave]

Well, hooking up the heater permanently means you are essentially running coolant through a small radiator all the time! not surprise. What i would do is keep your current set-up and NOT drill the thermostat, you should then see it move.

Also is your water temperature gauge electrical or capillary?

You have to have a hole in the thermostat to work as a bypass, but it doesn't have to be very large.

All mini heaters are normally on, (if the switch on your dash is in then it's on), this doesn't work as a thermostat bypass either, it's the wrong way!

Put one hole in the thermostat ring, and get that right, then check your electrical sender and gauge, and the connections.

If it comes to it, measure the coolant temperature by some other means.

Dave

[liirge]

Explain why its the wrong way round, hooked up like the OP has it at the moment