Z3 overheating.

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Pele no2
Joined: Tue 20 Feb, 2018 21:21
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  Z3 roadster 1.9i

Z3 overheating.

Post by Pele no2 » Sun 11 Nov, 2018 18:55

Hi,I’ve had my 2001 1900 z3 sport for approx 4 years. About 2 years ago it was taken out for the day, ran faultless until we met some slow traffic a few miles from home when I noticed the temp gauge in the red. I stopped, but in the end got towed home. I ran it to my local garage, whom put a new water pump, complete housing and a new belt etc, ran it for 4 hours on tickover and reported no problems. I took the car out last weekend for about 30 miles and within a couple of minutes of slow traffic it had overheated again, temp in the red.
I lifted the bonnet but I’ve never heard or seen the fan come on. I checked the radiator after slowly taking the cap off and it was full. Left it 30 mins then set off back home, all fine when running at speed. Got back home, checked the radiator and it was only about a third full, so I topped it up with anti freeze.
I have relocated so not sure where to take the car. I would like to do some basic checks before I send it in, can anybody give me some pointers, as it’s not easy to get under the car or get to the stuff under the bonnet as it all seems a bit tight to me.
Is the radiator at fault?
Thanks, Mark.

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colb
Joined: Sat 05 May, 2012 23:46
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  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: Z3 overheating.

Post by colb » Sun 11 Nov, 2018 19:06

Sounds like you have a leak when the system is hot and under pressure and loosing the coolant. Top the car up and run it up to temp then look at all rubber pipes and radiator for leaks. Check the footwell carpets to see if the heater matrix has sprung a leak. Your previous experience of overheating where the garage put in a new water pump may well point to a new leak in the system having developed. A garage could do a pressure test but you will end up paying for that to be done. If the car was running ok lets hope the head gasket hasn't blown.
When you run it up to temp check the fan comes on, if it fails to cut in then test that with 12v connected to the fan to see if it is working, if it spins up then suspect the temp switch that controls it.
Colb
1999 BMW 1.8 Z3
1998 Honda Deauville NT650V

Pele no2
Joined: Tue 20 Feb, 2018 21:21
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  Z3 roadster 1.9i

Re: Z3 overheating.

Post by Pele no2 » Sun 11 Nov, 2018 20:04

Ok, that’s great. I’m wondering if the temperature switch may be faulty then. Is this a simple thing to replace?
It doesn’t seem to leak water anywhere when parked up. I wondered if there was some kind of blockage maybe in the radiator due to the age of it also, so it’s not circulating.
I think I need to check the fan first job.
Should the car get that hot after being in traffic only for a few minutes?

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colb
Joined: Sat 05 May, 2012 23:46
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  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: Z3 overheating.

Post by colb » Sun 11 Nov, 2018 21:15

Getting hot quick in slow traffic should be regulated by the fan cutting in, will come in dependant on water temp and outside temp will also be a factor. Hot day and slow traffic will cause the temp to rise until it triggers the fan to come on. As soon as temp reduces the fan will cut off until the temp rises again to bring it back on again. Temp sensor is a screw in sensor on the radiator if your putting a new one in do it with engine cold and have new one to put in quick so you do't loose coolant.
The temp guage should be at the middle position 12 o'clock on the guage when up to temp usually stays rock steady at that position if it climbs the fan cutting in should bring it back down to the centre position. If you suspect a blockage then you will need to flush the system out using a hosepipe and back wash it. When refilling get the front of the car high as possible in order to get all the air out of the system.
We havn't mentioned the possibility of a faulty thermostat having failed in the closed position, if it has then that could be a cause of overheating. Only way of checking that is take it out and put a new one in.
Colb
1999 BMW 1.8 Z3
1998 Honda Deauville NT650V

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sirius-c
Joined: Wed 12 Dec, 2012 22:24
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  Z3 roadster 2.8
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Re: Z3 overheating.

Post by sirius-c » Mon 12 Nov, 2018 14:58

Have you checked the thermostat?
It sounds like this is the guilty one to me
1997 2.8L Z3 Roadster

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Designed or not designed, that is the question.

Boosh
Joined: Sun 30 Nov, 2014 22:40
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  Z3 roadster 1.9i

Re: Z3 overheating.

Post by Boosh » Wed 14 Nov, 2018 08:20

Hi,
In my experience, the over-heating and consequent head gasket blowing was due to a faulty Relay not triggering the fan. Expensive repair (new engine) for a cheap part!
Fingers crossed you caught it in time...

Boosh.

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dazthephot
Joined: Wed 09 Apr, 2008 19:58
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Re: Z3 overheating.

Post by dazthephot » Wed 14 Nov, 2018 21:16

Just to add my two Penneth. I had a similar issue which resulted in a week long investigation, replacement of the thermostat, water pump, radiator then eventually the head gasket. The first big thing I had to pay for after only 2 years of ownership.
Turns out the original fault was a blocked radiator and BMW couldn’t find it until after they’d replaced everything.
Thankfully another 10 years down the line the car is still running pretty sweet.

You could try a rad flush or even replacement??? I don’t know how to test for a blocked radiator.


Sent from my iPhone using Tapatalk Pro

Pele no2
Joined: Tue 20 Feb, 2018 21:21
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  Z3 roadster 1.9i

Re: Z3 overheating.

Post by Pele no2 » Mon 06 May, 2019 19:55

Hi, just an update on the overheating z3.
Took it to my local garage, the guy has just done my van and his pricing was realistic.
Anyhow, I took him a new hella fan and Kerr nelson fan switch.
He fitted them both, filled up and then left it a few hours, temp guage steady at 12 o’clock. I ran it home, no problems, even came back a few days later to the garage over something else and let it idle for 20 mins the fan coming on several times.

All seemed well, till a couple of days ago, set off on a 75 mile trip. 4 miles in, the car temp ran into the red, light coming on. I stopped it immediately and lifted the bonnet to find coolant everywhere. I let it cool down and checked radiator level and it was virtually empty.
I left it 15 mins, started it then drove it home, temp guage went back to 12 and it never missed a beat??

The mechanic mentioned to me that something was in the original coolant, that repairs head gaskets, the smell and small bits of something that he has seen before.

When I was rescued a couple of years ago, the AA guy had a temperature sensor and said the engine block had a different temperature on part of it, which seemed strange?

Does anybody think that this previous ( I think) head repair has clogged up something in the engine block causing some kind of problem allowing the coolant to go round the full system?

I’m at my wits end to be honest, as I have no idea where to go from here?

New rad, thermostat, new water pump, belt and complete thermostat housing, but still over heating.

Mike Fishwick
Joined: Fri 19 Jun, 2009 11:27
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  Z3 roadster 2.8
Location: Daglan, France

Re: Z3 overheating.

Post by Mike Fishwick » Tue 07 May, 2019 09:41

You have not mentioned replacing the thermostat - are you confusing it with the thermo switch for the electric fan?

Even if the electric fan (assuming that you have air conditioning) is not operating, the viscous-coupled fan is capable to keeping the engine at a decent temperature.

I would look for coolant leaks, maybe inside the heater, as such a leak woud go down the condensate drain and onto the road.
A Z3 is not just for Christmas - it's for life!

Pele no2
Joined: Tue 20 Feb, 2018 21:21
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  Z3 roadster 1.9i

Re: Z3 overheating.

Post by Pele no2 » Tue 07 May, 2019 17:50

The thermostat was changed a couple of years ago when the water pump and belt was replaced.
I was talking to a colleague this morning whom has an engineering business and he went through how the system works and came to the conclusion that the problem is definitely the head gasket, and the head will be warped. He made a valid point that after 4 miles with the temperature at around 3 degrees outside the only water heating up would be running round the cylinder head and it has just forced the coolant out under pressure.
I then spoke to the mechanic without mentioning my earlier call and he said, everything has been done so the head gasket is the only thing left which is the most likeliest.
So I’m into a few hundred quid now, but don’t feel I have much choice, as I have no previous history of the car even though the mileage is less than 60k. :shrug :shrug

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colb
Joined: Sat 05 May, 2012 23:46
Posts: 662

  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: Z3 overheating.

Post by colb » Tue 07 May, 2019 19:51

Someine mentioned earlier to do a gas test on the radiator to see if there are exhaust gases getting into the water from a blown head gasket. https://www.ebay.co.uk/itm/Car-Combusti ... Sw9GhYmf2r
Also a compression test would be worthwhile and may point to where the gasket has blown.
If you tear the head off and have it skimmed and leak checked probably best to put a new thermostat in as well despite yours being in for only 2 years. At least you will be starting with a level playing field.
Colb
1999 BMW 1.8 Z3
1998 Honda Deauville NT650V

Pele no2
Joined: Tue 20 Feb, 2018 21:21
Posts: 10

  Z3 roadster 1.9i

Re: Z3 overheating.

Post by Pele no2 » Wed 08 May, 2019 20:32

I’m planning to do just that, have the head pressure tested and skimmed. I don’t want to think of the cost at this stage, but it’s no use to anyone in this state.
I’ll have an update in a few weeks.

Thanks for the replies.

Howard Adams
Joined: Mon 10 Oct, 2016 16:39
Posts: 57

  Z3 roadster 3.0i

Re: Z3 overheating.

Post by Howard Adams » Fri 10 May, 2019 14:20

Hi, if you get a gas check to see if there are any gases in the water/radiator, if there is, it’s definitely got a head concern.
In a previous life I used to work for Land Rover and this was the test we always did on the K series engine. A. compression check will also tell you if there is anything else wrong(hopefully not)
Once the head is off you also have the debate whether to decoke the head etc...yes I know money grows on trees and these things do get potentially expensive.
H

joneseric
Joined: Wed 19 Jun, 2013 20:10
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  Z3 roadster 2.8
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Re: Z3 overheating.

Post by joneseric » Sat 18 May, 2019 20:58

I am coming in on the thread late, my Z3 1.9 suffered overheating after a thermostat replacement. If I am teaching to suck eggs, please accept my apologies. Refilling the 1.9 M44 engine with coolant has to be carried strictly in accordance with the procedure detailed in the workshop manual and its a pain, failure to carry out the correct bleeding procedure will cause air-locks to develop and overheating. It took me two attempts and I’m a fairly experienced mechanic, albeit aircraft engines!

Good luck

Eric

Pele no2
Joined: Tue 20 Feb, 2018 21:21
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  Z3 roadster 1.9i

Re: Z3 overheating.

Post by Pele no2 » Sat 25 May, 2019 17:17

Hi Eric, thanks for the advice. At this moment in time, I’ve had the head skimmed and pressure tested and should be all going back together in the next week or so by the mechanic that’s stripped it down.
He did say the head had been leaking in several places, and the guy that skimmed it said there was evidence of it leaking also in several places, so im assuming once it’s all back together and bled correctly it will be all sorted!
Thanks for all the comments, i’ll Let you know the outcome.

Mark.

Andyboy
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Re: Z3 overheating.

Post by Andyboy » Sun 02 Jun, 2019 09:22

I've never had a problem bleeding these, but the key is correct filling with coolant. If you just tip it down the expansion tank, it will airlock as air cannot escape at the same rate coolant is going in. I always pop the top hose off the radiator first, and add antifreeze down the expansion tank (rad cap) with the bleed screw out. Once that's in, continue with water, both in the expansion tank and some down the top hose. Once the top hose is showing a coolant level, stick it back open, set heater to hot, fire it up and run it at 2500 rpm for 2 mins. Once the heater's blowing hot air, you're done. I leave the bleed screw slightly open so once it starts bubbling and escaping from there, tighten it up.

Filling/bleeding takes about 5 minutes.

6 cyls can be a bit harder - I remove the fan switch or it's blank on the drivers side of the rad to aid filling.

Pele no2
Joined: Tue 20 Feb, 2018 21:21
Posts: 10

  Z3 roadster 1.9i

Re: Z3 overheating.

Post by Pele no2 » Sun 02 Jun, 2019 19:31

Hopefully, the car will be ready this week. I’m sure he will have it idling outside for a couple of hours to make sure it’s all ok.
Fingers crossed.

Pele no2
Joined: Tue 20 Feb, 2018 21:21
Posts: 10

  Z3 roadster 1.9i

Re: Z3 overheating.

Post by Pele no2 » Sat 29 Jun, 2019 16:10

Just an update on the z3.
Picked up the car this afternoon, after having the head skimmed and all put back together. All seems well, temperature gauge steady at 12.
Total cost, £70 for head skimming from a pal of mine, and £530 for the engine stripping and rebuilding again c/w all new gaskets, antifreeze and some bolts, some new petrol pipes and vacuum hoses.
That sounds a decent price to me, only time will tell, plus the mechanic did say that it would cure several small oil leaks that were there, as some of the baskets had gone.

Definitely going to use it now this summer, if it’s only to get some of my money back in driving it!

joneseric
Joined: Wed 19 Jun, 2013 20:10
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  Z3 roadster 2.8
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Re: Z3 overheating.

Post by joneseric » Sat 06 Jul, 2019 13:38

That is excellant news.

Rgds

Eric

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