Advice | Help Needed

justleicaman

Regular Member
Joined
Jul 26, 2025
Points
13
Recently I joined this terrific forum having come into possession of the ‘FROG’ 99 1.9 16V. Actually there is another Z3 a 1.8 with 58000 miles. The two cars were part of the estate of a good friend who passed away 1 yr ago. The two cars were acquired by my friend as projects. I’ve undertaken the job of getting the 1.8 back on the road for his mum & dad and I’ve acquired the Fiji Green Car for a lengthy rebuild.
I’ve now discovered that the 1.8 has a problem! It ticks over smoothly, and temp remains stable on tickover, however, drive the car for a very short distance or increase the revvs for 30 seconds and the temp gauge is soon in the red. There’s a bad misfire when under load too which is not present on tickover. I’m suspecting a blown head gasket. Before I go down that rabbit hole can anyone suggest other causes I might investigate?
Cheers.
 

Zephyr

Zorg Guru (III)
Supporter
Joined
Aug 10, 2022
Points
139
Hi, get a decent scanner and save yourself from a lot of trial and error diagnosing.
Other than that look for signs like milky oil, white exhaust smoke, or bubbles in the radiator.
Start with the cooling system (thermostat, water pump, radiator, coolant level, and bleeding) and ignition/fuel checks (plugs, coils, fuel filter, MAF, intake boot), as these are more common and less invasive than a head gasket replacement.
A head gasket failure is less likely unless you see clear signs like coolant loss or contamination as I said above.
 

ChrisD

Zorg Addict
Joined
Nov 29, 2023
Points
54
Location
Evesham
Model of Z
M44
I’d recommend an OBDII scan before embarking on major engine work. Even if it reveals nothing, at least you have a baseline to start from.
 

ChrisD

Zorg Addict
Joined
Nov 29, 2023
Points
54
Location
Evesham
Model of Z
M44
Cheap scanners are fine these days. See what I use here:
Data logs are stored on your device with this method. Sorry, I can’t comment on mycarly - I have no experience of it.
 

ChrisD

Zorg Addict
Joined
Nov 29, 2023
Points
54
Location
Evesham
Model of Z
M44
The UK spec M44 doesn’t have an OBDII port so needs the 20pin adapter. The later car ‘should’ have the OBDII port but, as always with these things, best to take a quick look yourself - just in case you have yourself a ‘special’.
 

ChrisD

Zorg Addict
Joined
Nov 29, 2023
Points
54
Location
Evesham
Model of Z
M44
If you check the link I posted, you’ll see the vehicle 20pin diagnostic port that has the OBDII adapter connected to it. It is located by the coil pack on the UK spec M44. On other models it can be located on the other side of the engine bay, by the fuse box. As there are other 20pin connectors in the engine bay, you are looking for the one that just has a cap on the top - no other wires coming from it - only to it.
 
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