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Old 12-12-2010, 22:33   #1
Southside
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ZT 1.8-T Coolant system pressurising

Asking on behalf of a friend.

2005 ZT 160 1.8-Turbo

Car was driving fine with no problems. Then just lately the coolant system has started presurising. Temp guage will hit the red then drop back down again to half way, stay there for a few more miles then shoot back up to red again and so on.

No oil or coolant loss. Coolant system has not been touched so cant figure out how it seams to have gotten an airlock in it?

Any idea's?
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Old 12-12-2010, 23:45   #2
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The gauge on MGR cars is legendary for being unreliable! On the 1.8T I think I'm right in saying it only moves when the engine temp hits 115C which is symptomatic of losing fluid.

If you're certain there's no mayo in the filler cap or rising levels in your dipstick I'd try loosening the bleed valve and top up with a correct % OAT anti-freeze just in case.
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Old 12-12-2010, 23:53   #3
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I think you are mistaken. There will be coolant loss. If the system has been building excessive pressure, it will have lost fluid.
How are you checking? It has to be done with the engine cold, on level surface, the water level in the expansion tank has to be above the MIN mark, with a maximum at MAX.
Don't overfill.
It has not developed an air lock, it has simply lost water. There are a number of prime candidates for that, T-piece cracking, can be difficult to spot, replace with metal!!! inlet manifold gasket, replace! water pump, replace, rotten hoses, replace, expansion bottle cap, replace: check for any other leak.!!!

The only other realistic option for what you are seeing, is a stuck thermostat, and that is much less likely in my view.


So tell you friend to check the water level, daily!
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Old 13-12-2010, 00:16   #4
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What he said ^

Missed the point about it being a friend's car. Tell them they MUST check the water level properly. Looking into the expansion tank when cold, the Min/Max level indicators are right at the bottom of the tank and only about 5mm apart.

Overheating serious enough to move the temperature gauge into the red MUSt be investigated, it's just not a normal phenomenon!
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Old 13-12-2010, 00:24   #5
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Cause needs to be identified before more serious overheating causes damage to the engine. As in kaiser's list, the first thing I'd check is the Coolant Bottle Pressure Cap ~ they do not last forever and are not expensive so replace anyway. Get the genuine MG-R one ideally. If that doesn't improve things, water pump next suspect.... another prime suspect for coolant loss is the inlet manifold gasket although, I'm only familiar with those on the normally aspirated K-Series ~ the Turbocharged may have a different arrangement to cope with the boost pressure in the plenum chamber...

We have and have had K-Series engines in the family for close on twenty years. In a healthy engine, the needle on the temperature gauge reads just below halfway ~ if it goes noticeably above halfway, something needs investigating...

In a healthy engine, the cooling system runs at a higher pressure once the engine warms up. If there's a leak ( split hose or worn water pump for instance ) in the cooling sysyem, that normal running pressure is never reached and so the coolant can boil prematurely.
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Old 13-12-2010, 16:53   #6
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To be honest guys im a qualifed mechanic. I know how to check a coolant level and its not dropped. Its still just under max where it always has been. This is whats confusing me

Coolant has not been topped up. Its more than likely still on the coolant it left the factory with.

I've also owned over 30 different MG-R's all with k-series fitted apart from 3 L-series and i've always done my own work on them, everything from minor issues to full engine rebuilds. But i've never come across this problem before thats why im asking the question on here.
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Old 13-12-2010, 16:58   #7
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Its more than likely still on the coolant it left the factory with.

If that's a possibility, to be on the safe side, drain all the coolant and fill with fresh .... as recommended by all manufacturers.

You with your experience may already know that, but others searching with similar problems finding this thread may not.

That way we all can learn.

..

Fluctuation of the K-Series temperature gauge needle in the way you describe I'd bet a few quid means there's air in the system where it should not be.
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Old 13-12-2010, 17:04   #8
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I would change the PRT or thermostat if no PRT is fitted
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Old 17-03-2011, 15:11   #9
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Hi all, I'm a newby so go easy on me! Apologies in advance!
Sorry to cut in on this subject, but I too have the exact problems with my ZT 160 T. I've replaced in the last week .... headgasket, waterpump, radiator, t piece (top of rad), thermostat and ALL gaskets..... and still I have pressurised pipes and overheating. Also, I experience a cold rad and the fans do kick in. The only thing I haven't changed is the PRT. Could the PRT be the cause of the fault? I should add that i think there may be air in the system as when I start her up, I hear a water type splash behind the dash.
Any help or advise would be appreciated as I'm close to cutting my wrists!!!
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Old 17-03-2011, 15:52   #10
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Originally Posted by deemo1975 View Post
Hi all, I'm a newby so go easy on me! Apologies in advance!
Sorry to cut in on this subject, but I too have the exact problems with my ZT 160 T. I've replaced in the last week .... headgasket, waterpump, radiator, t piece (top of rad), thermostat and ALL gaskets..... and still I have pressurised pipes and overheating. Also, I experience a cold rad and the fans do kick in. The only thing I haven't changed is the PRT. Could the PRT be the cause of the fault? I should add that i think there may be air in the system as when I start her up, I hear a water type splash behind the dash.
Any help or advise would be appreciated as I'm close to cutting my wrists!!!
The water splash behind the dash may be unconnected. Check your Plenum chamber is not flooded! or you will also be replacing your ECU Dave
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Old 17-03-2011, 15:59   #11
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Thanks for advice Dave, just been reading up on that subject and it looks like a common problem. I'll check it out the weekend! Thanks again.
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Old 18-03-2011, 01:07   #12
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Quote:
Originally Posted by deemo1975 View Post
Hi all, I'm a newby so go easy on me! Apologies in advance!
Sorry to cut in on this subject, but I too have the exact problems with my ZT 160 T. I've replaced in the last week .... headgasket, waterpump, radiator, t piece (top of rad), thermostat and ALL gaskets..... and still I have pressurised pipes and overheating. Also, I experience a cold rad and the fans do kick in. The only thing I haven't changed is the PRT. Could the PRT be the cause of the fault? I should add that i think there may be air in the system as when I start her up, I hear a water type splash behind the dash.
Any help or advise would be appreciated as I'm close to cutting my wrists!!!
Bleeding the cooling system on the K-Series can be tricky.

If everything else is in order following the repairs, from what you say you still have air in the cooling system. What you describe are almost certainly classic signs of air still in the system where it should not be. Ideally, the only air in the system should be in the top half of the Coolant Expansion Bottle... to allow for the expansion of the coolant as it gets hot. Some pressure in the system is normal. Too much pressure is a sign that something is not right.

I have described how I bleed the system on K-Series to get all that air out from where it should not be with 100% success after the first time I did the job, the engine overheated because of air still in the system.

Search for the bleeding technique I use on this site. I have described it several times at length on some threads.

It should work for the Turbocharged K-Series although I've not worked on one of those, only the normally aspirated K-Series cars.
.
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Old 18-03-2011, 07:51   #13
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Thanks for the reply MGJohn. Is this the technique you use.....

Take out the bleed screw on coolant rail.
one of the secrets of bleeding the K-series is to slowly trickle the coolant into the expansion bottle, not jug it in and hope for the best.
You want the heater temp control knob set to max heat, if you don't do this you will have air-locked in the heater matrix.
When nothing but coolant is streaming out, replace the bleed screw, keep slowly filling the tank until at correct level. Give the hoses a good squeezing. Top up cap on, and start engine, within a few minutes, the heater with the fan on should be throwing out ever warming air, getting hotter by the minute......................... assuming you didn't have a bit of a furred up heater matrix to start with.
If not, stop engine and get squeezing the hoses some more, and check the bleed screw in case there is more air in the coolant rail.
The above is the normal approach.................

This is a superior method, supplied by ASHY.
I've done it a good few times now and never had a problem with airlocks. Slow and continuous filling is the key. No good just filling a jug up, pouring that in and then filling it up again as that's how air gets trapped.
My method is to use a syphon. I use a fishtank syphon, about 3-4, as I don't want to get any in my mouth, but any old bit of hose pipe will do, just don't suck it into your mouth.
Fill a bucket or bowl with the right amount of coolant/water mix and then put one end of the tube in the coolant tank and one end in the bucket. Undo bleed screw and then just wait until a good flow of liquid comes through.
Run the engine for a bit without the expansion tank cap on and then switch off and allow to cool.
Bleed again and then take the car for a run and then a final bleed when cool.
I don't usually get any air on the second bleed with this technique.
I will add that he assumes that anybody reading this, would have the bleedscrew out as above method and would have their heater set to hot............... and run the car with the heater on, as a warning of air-lock.
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Old 18-03-2011, 18:46   #14
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Originally Posted by deemo1975 View Post
Thanks for the reply MGJohn. Is this the technique you use.....

Take out the bleed screw on coolant rail.
one of the secrets of bleeding the K-series is to slowly trickle the coolant into the expansion bottle, not jug it in and hope for the best.
You want the heater temp control knob set to max heat, if you don't do this you will have air-locked in the heater matrix.
When nothing but coolant is streaming out, replace the bleed screw, keep slowly filling the tank until at correct level. Give the hoses a good squeezing. Top up cap on, and start engine, within a few minutes, the heater with the fan on should be throwing out ever warming air, getting hotter by the minute......................... assuming you didn't have a bit of a furred up heater matrix to start with.
If not, stop engine and get squeezing the hoses some more, and check the bleed screw in case there is more air in the coolant rail.
The above is the normal approach.................

This is a superior method, supplied by ASHY.
I've done it a good few times now and never had a problem with airlocks. Slow and continuous filling is the key. No good just filling a jug up, pouring that in and then filling it up again as that's how air gets trapped.
My method is to use a syphon. I use a fishtank syphon, about 3-4, as I don't want to get any in my mouth, but any old bit of hose pipe will do, just don't suck it into your mouth.
Fill a bucket or bowl with the right amount of coolant/water mix and then put one end of the tube in the coolant tank and one end in the bucket. Undo bleed screw and then just wait until a good flow of liquid comes through.
Run the engine for a bit without the expansion tank cap on and then switch off and allow to cool.
Bleed again and then take the car for a run and then a final bleed when cool.
I don't usually get any air on the second bleed with this technique.
I will add that he assumes that anybody reading this, would have the bleedscrew out as above method and would have their heater set to hot............... and run the car with the heater on, as a warning of air-lock.
The first description is close to the method I use. Alternate squeezing of the top and bottom radiator hoses for a minute or two whilst the engine is running ( be careful ) does the trick for me with the K-Series.
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Old 19-03-2011, 04:49   #15
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The first description is close to the method I use. Alternate squeezing of the top and bottom radiator hoses for a minute or two whilst the engine is running ( be careful ) does the trick for me with the K-Series.
Thanks for your help, I'm going to give it all a go the weekend so wish me luck.... I'll let you know how I get on. Many thanks!
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Old 23-03-2011, 20:30   #16
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Someone here fitted some 3 thou shims to their too low cylinder liners ( flush with block ) and it appears to have worked well. Search this forum and have a read up ~ it may be the answer to your problem. It's a good, informative and well illustrated read as well.


This one ...

http://forums.mg-rover.org/showthrea...highlight=shim

also see these pictures :~

http://forums.mg-rover.org/showpost....6&postcount=36
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Old 24-03-2011, 15:19   #17
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That looks interesting, I'm going to have a chat with my mechanic friend and see what he thinks. I'm desperate to get this car running now. There may be light at the end of the tunnel after all! Thankyou very much for the info, much appreciated.
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Old 24-03-2011, 15:56   #18
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Looks like my bottom end is buggered! The liners have sunk - - -
How do you know that?

TC
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Old 24-03-2011, 18:28   #19
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Looks like my bottom end is buggered! The liners have sunk and it looks like air is getting into the cooling system.
Cheer up! No need to be sad ... at the moment...

Numerous reasons why air can get into the system even if not touched. Prime suspect being a worn coolant (water) pump losing coolant allowing air into system.

Quote:
Originally Posted by T-Cut View Post

Quote:
Originally Posted by deemo1975 View Post

Looks like my bottom end is buggered!
.
..How do you know that?

TC
Good question TC.

Difficult to be certain until cylinder head is removed to reveal the liners. Could be a valve not seating properly on that cylinder. Guesswork until then.

Quote:
Originally Posted by OP-Southside
....
.
Coolant system has not been touched.
.
Although the cooling system has not been touched as stated in the original post, how can the OP be certain if its not his car? Again, water pump always a prime suspect.
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Old 25-03-2011, 09:33   #20
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If you are going to shim the liners like I did on mine, have in mind that this only fix engines that left the factory with low liners. If your liners have dropped due to overheating/annealing of the block, shimming will not help as the liners will drop further. The MLS gasket requires a liner protution of 0,002"-0,004" to give a good seal. If lower, it has been recommended to use the elastomer gasket Payen BW750. This one is more tolerant to liner heigths ans also uprated compared to the OEM one.
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