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Old 31st March 2021, 10:50   #31
paulh260260
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Following yesterdays coolant refill, and now the car is up on ramps I've had a good feel of the hoses and rad.

The bottom hose as well as the bottom of the rad is cold, so clearly a blockage somewhere. Obviously just flushing with water didn't do the trick

My initial thought is using one of the commercially available radiator/coolant flushing solutions out there probably Holts.

Remember I'm not just flushing as a maintenance but trying to unblock the rad ( or a hose somewhere) so are there specific ones that do the job better...I've had a look online but I can't get past the marketing hype as all seem to do absolutely everything apart from lower your cholesterol!!!

(BTW I've definitely not put in any devils liquid however I don't know if any has been added by previous owners)

Cheers

Paul
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Old 31st March 2021, 11:59   #32
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The bottom hose as well as the bottom of the rad is cold, so clearly a blockage somewhere.
Hello Paul,

Yes, it's either down to a previous dose of K-seal or your thermostat isn't opening.

To start with, how about disconnecting top and bottom radiator hoses, inserting a hose pipe into the top and observing the flow out of the bottom?

I take it that this time you have drained the cooling system fully, including loosening the cylinder block plug, and following the MGR procedure exactly.

Simon
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Old 31st March 2021, 14:29   #33
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Hello Paul,

Yes, it's either down to a previous dose of K-seal or your thermostat isn't opening.

To start with, how about disconnecting top and bottom radiator hoses, inserting a hose pipe into the top and observing the flow out of the bottom?

I take it that this time you have drained the cooling system fully, including loosening the cylinder block plug, and following the MGR procedure exactly.

Simon
Cheers Simon

Yep I did everything exactly as per procedure, cylinder block plug removed, bottom hose removed ,header tank raised ( I don't think I'd dare come back to you if I hadn't followed procedure)

With regard to the thermos, the top hose is very hot doesn't that suggest the thermos is opening?

Paul
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Old 31st March 2021, 14:40   #34
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Originally Posted by SD1too View Post
Hello Paul,

Yes, it's either down to a previous dose of K-seal or your thermostat isn't opening.

To start with, how about disconnecting top and bottom radiator hoses, inserting a hose pipe into the top and observing the flow out of the bottom?

I take it that this time you have drained the cooling system fully, including loosening the cylinder block plug, and following the MGR procedure exactly.

Simon

I wonder if it was run up to thermostat opening temp ? what the the rad top and top hose temp feel like in comparison to the bottom ? was there a noticeable increase in pressure felt by squeezing the hoses, not scientific but can give some indication, how long was the engine run for at least 20 mins ?



I think nothing would be lost and there may be something to gain by having a full coolant system test, by the book.


When cold, pressure test the cap and system, if no leaks, drop in pressure or sign of coolant loss over at least 10 mins, release the pressure, start the engine at a fast idle then whilst observing the pressure rise, quickly and constantly keep going round all hoses, radiator, stat housing etc. with an i.r. temperature gun noting any rises in temp, or none, keeping an eye on the pressure gauge, that it doesn't go over cap blow off pressure, until the fan comes on, then back to normal idle till the fan goes off, again monitoring the temperatures.


Once the fan stops, switch off and monitor pressure drop until stone cold, several hours,there may be a very small amount of residual pressure too low to show on many coolant test gauges, but may be heard as a small hiss, but shouldn't be readable.



If you are methodical with the i.r. gun you will be able to follow the coolant heat flow through the system and see if there are actually areas where the temp increase is minimal compared with elsewhere, or where hot water would be expected and also note when the stat opens or not, everything being equal, by the time the fan comes on at max. temp, all the components, hoses etc should be be around the same temp, but allow for a small temp drop through the radiator, even before the fan comes on.


A simple radiator flow test can be done with two people and a bit of ingenuity, remove the bottom hose and ' bung ' up the rad spigot, if possible, slacken the top hose at the radiator and remove it from the engine, spin the hose round to point upright to act as a funnel, slowly fill with water to the top of the top hose and whip the bottom bung out, it should empty pretty rapidly and be clean.
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Old 31st March 2021, 14:51   #35
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Originally Posted by Ducati750cc View Post
I wonder if it was run up to thermostat opening temp ? what the the rad top and top hose temp feel like in comparison to the bottom ? was there a noticeable increase in pressure felt by squeezing the hoses, not scientific but can give some indication, how long was the engine run for at least 20 mins ?



I think nothing would be lost and there may be something to gain by having a full coolant system test, by the book.


When cold, pressure test the cap and system, if no leaks, drop in pressure or sign of coolant loss over at least 10 mins, release the pressure, start the engine at a fast idle then whilst observing the pressure rise, quickly and constantly keep going round all hoses, radiator, stat housing etc. with an i.r. temperature gun noting any rises in temp, or none, keeping an eye on the pressure gauge, that it doesn't go over cap blow off pressure, until the fan comes on, then back to normal idle till the fan goes off, again monitoring the temperatures.


Once the fan stops, switch off and monitor pressure drop until stone cold, several hours,there may be a very small amount of residual pressure too low to show on many coolant test gauges, but may be heard as a small hiss, but shouldn't be readable.



If you are methodical with the i.r. gun you will be able to follow the coolant heat flow through the system and see if there are actually areas where the temp increase is minimal compared with elsewhere, or where hot water would be expected and also note when the stat opens or not, everything being equal, by the time the fan comes on at max. temp, all the components, hoses etc should be be around the same temp, but allow for a small temp drop through the radiator, even before the fan comes on.


A simple radiator flow test can be done with two people and a bit of ingenuity, remove the bottom hose and ' bung ' up the rad spigot, if possible, slacken the top hose at the radiator and remove it from the engine, spin the hose round to point upright to act as a funnel, slowly fill with water to the top of the top hose and whip the bottom bung out, it should empty pretty rapidly and be clean.
Hi Ducatti

Yep it was run to opening temp, the top hose started getting hot at around 88 degrees.

I ran it for about 15 minutes by which time it was at 102 degrees so I switched off.

I'm afraid you've lost me regarding the pressure test and IR gun, haven't got either a tester or an IR gun. Is this something that a garage should be able to help with or are they relatively inexpensive items to purchase?

With regard to the spigot is that what the breather hose goes into on the drivers side of the rad?

Cheers

Paul
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Old 31st March 2021, 15:01   #36
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With regard to the thermos, the top hose is very hot doesn't that suggest the thermos is opening?
The thermostat isn't where you expect it to be Paul. It controls the flow from the bottom of the radiator back to the engine. The top radiator hose is fed continuously from the cylinder head via the curved plastic pipe. So the answer to your question is no.

Your next task is to find out why there's no (or inadequate) flow through the radiator. There's no point in flushing it if the cause turns out to be a faulty thermostat.

Simon
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Old 31st March 2021, 15:15   #37
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If your cooling system's like this -





- then I think I'd cast my eye over the oil cooler. The coolant around the lower radiator won't get warm if there's a bockage in the oil cooler.



TC
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Old 31st March 2021, 16:01   #38
paulh260260
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If your cooling system's like this -





- then I think I'd cast my eye over the oil cooler. The coolant around the lower radiator won't get warm if there's a bockage in the oil cooler.



TC
Thanks TC

Bypassing the oil cooler seems to be something that should be done but I'm not sure how to do this specifically.

Is there a detailed how to anywhere ( I cant find one and I've searched every where.

Cheers

Paul
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Old 31st March 2021, 16:08   #39
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Hello Paul, by-passing the oil cooler is often discussed, but I don't recall any detailed instructions, tho there may be some general description. I'd suggest doing a key word search to sift out the threads.


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Old 31st March 2021, 18:20   #40
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Hello Paul, by-passing the oil cooler is often discussed, but I don't recall any detailed instructions, tho there may be some general description. I'd suggest doing a key word search to sift out the threads.


TC
Yep already spent a few hours at the beginning of this problem looking for some more instructions but to no avail other than "swap pipes" or "bypass the cooler".

Worryingly the Haynes manual as well as RAVE begins any talk about working on the oil cooler with the dreaded phrase "remove the auxiliary timing belt" something I'm not happy tackling myself!!

Paul
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