What went first i wonder

[Scarlet Devil]

Driving on the M5 yesterday doing about 65mph the I noticed a big puff of white smoke out of what I thought was the exhaust. Typically it was on a section where you couldn't pull over. I put hazards on and slowed down to about 30. Temp was normal and car running as good as before after a major rebuild in march. About 1 mile to services and hard shoulder appeared then temp gauge suddenly went to the top and main display flashed up engine over heating as I pulled over. On inspection the hose from the plastic 't' piece going down to the PRT had a series of what looked like pin holes in it on the straight bit just before the PRT. Luckily I had a container of water with me and some kit to bleed the system. Long story but managed to get the car home and have just replaced the offending hose that I happened to have a spare one of. Now on checking for leaks I notice its coming out from the bottom pulley so im presuming the water pump had now gone. Im wondering if the PRT is stuck shut or the pump leaked fluid causing overheating or the hose when first creating the leak from pump. Oil seems fine and engine running normally cold so im hoping no more damage.

[chipsceola]

The same hose went on mine last spring, I stopped within 200yds when coolant level light came on, AA man replaced at scene, failed to spot low speed fan not working, and then didn't bleed system properly, result HGF within next 4 miles.

I had been caught in a traffic jam for about a mile, just before the hose failure, wondering if lack of cooling at low speed with no fan caused extra pressure to pop the hose, and that sounds a bit like yours I think?

[Scarlet Devil]

Im now thinking that ive not noticed the fan coming on in traffic or extended stationary, yet it works with demist and climate control. Having said that it came on when it overheated. I looked through the grill and cant see a resistor where the 2 holes are. Being an 04 model would I have the 2 speed fan with resistor or the 3 speed fan without one. I know they changed them late 03 but is mine a late reg old type.

[chipsceola]

Mine is 03 non-PRT with 3 wire 2 speed fan but manufactured Nov02, when my fan went I bought a 2-speed with gold resistor fitted from an 05 ZT and that was a straight swap. However am sure Jules, T-Cut or Artic will be along soon to say what type yours should be.

[SD1too]

Being an 04 model would I have the 2 speed fan with resistor or the 3 speed fan without one.
Yours will be a 2 speed fan. There were two types: with and without resistor. The 3 speed motor was fitted only to the diesel & KV6.

Simon

[SD1too]

... wondering if lack of cooling at low speed with no fan caused extra pressure to pop the hose ...
I think that's a sound theory Chips. When the low speed has failed, the engine reaches 112 degrees C before the fast speed takes over. Then you're only three degrees away from the gauge moving up towards the warning of overheating.

Simon

[Scarlet Devil]

Its looking like a 2 speed without a resistor then. I had an idea the slow speed wasn't cutting in as much but didn't want to prove the point by letting it just idle to see if it kicks in.. So whats a remedy for getting the slow speed working again. Don't fancy a repeat of what I had. Ive used up my stock of spare hoses now. Plus I think the water pump has sprung a leak. Inner wheel arch panel off tomorrow I think so I can check it out.

[chipsceola]

See post #4 mine came with uprated gold resistor at a good price from [email protected] the later 2 speed with gold resistor is very reliable and I am sure any of the traders on here will have tested before removing for sale.

Either contact them direct or place an advert in Items Wanted section on this forum.

[SD1too]

So whats a remedy for getting the slow speed working again.
Hi Charlie,

Before jumping to conclusions you need to be sure that the slow speed has indeed failed. Do this by starting the engine from cold and pressing the windscreen 'demist' button on your air conditioning control panel. Now go to the front of the car and listen at the radiator grille. Is the fan running? Report back and we'll take it from there.


Plus I think the water pump has sprung a leak. Inner wheel arch panel off tomorrow I think so I can check it out.
That's a good move. Obviously a coolant leak has to be repaired promptly, particularly on the K1.8 which has a small coolant capacity.

Simon

[Scarlet Devil]

Ok the wheel arch liner has been removed. Topped header tank up and removed bleed screw so coolant would circulate. had engine running a while with no leak and also nothing coming out of bleed hole then all of a sudden the pump started to leak. Seemed like it was coming from all round the mated face so presume the rubber "O" ring has let go. Yes the fan works with the demist or climate control on. When I first had the car I noticed the fan coming on now and then as normal but had become aware of the fact it was not coming on through normal running of late so I tried the demist at the time and it worked then. It was only a couple of weeks ago while doing my usual engine inspection I noticed the short hose between the "T" piece and the condenser elbow had a split in it, so I changed that and the original clips for jubilee clips. So I was weary while giving the car a run when this bottom hose went. Just seems like its been putting the hoses under extreme pressure. My thinking is its either the PRT is stuck closed or the water pump is failing to circulate properly. I bled the system each time so don't think it was an air lock causing it.

[SD1too]

O.K. Charlie, so renew the water pump gasket/seal first.

Then check that, after the engine rebuild last March, a conventional 'stat wasn't fitted to the housing at the engine block. Your PRT should be the only thermostat you have. Another member has just found himself in this situation: two thermostats!

And remember that the bleed screw is for venting air during the filling process. It should not be open when the engine is running. I recently posted in another thread the full MGR procedure for the 1.8 engine.

Simon

[Scarlet Devil]

Thanks for that. A pump will be ordered. Looks a bit of a pain to do but should be ok. Im aware of the original thermostat position but must admit ive not checked that yet as its been running fine from rebuild up until now. Some great help from this site, most appreciated.