Got decent compression test result. 155, 150, 150, 155.

Can still see some gritty material post fuel filter so the next job will be to remove the fuel tank and clear out the lines and injectors. Should keep me busy for a while. Getting the tank out is a really crappy job.

Still to do the petrol tank, but has been OK to drive for a few hundred miles since the rebuild. Other than a "sputtering" noise from the exhaust when decelerating which I suspect is related to the fuel and injectors.

The car seems to run a shade under 90°C for ~15 miles then slowly gets hotter and struggles to come down, although ive not let it go over 105°C out of fear of causing damage. I have a temp sensor on the out of the radiator and it seems to fluctuate between 50 and 70 depending on driving conditions.

How hot it "too hot" for the 1.8 vvc engine? Is it worth removing the front number plate to allow air to go over the radiator? Not sure I understand why the engine is getting slowly warmer when the post radiator water is only 50C.

Have you checked thermostat, water pump or any blockages like from a collapsed hose?

I'm surprised that the radiator temp is so low. Are you running a prt, or a thermostat?

Does the cab heater matrix get hot?

I would only think you'd need more air through the radiator if it got too hot, not too cold.

Is everything definitely fully bled?

More questions than answers, but might point you in the right direction.

On Board Diagnostics (OBD) exists on Rover Modular Engine Management Systems (MEMS) since 1990. The earlier the system, the less information available via the diagnostic socket. It is invaluable for, well, diagnostics. My car is based on a 1990 Metro Gti with the MEMS 1.6 and I can accurately record engine temperature to one degree whilst road testing. I felt I had a lack of performance, and the diagnostics showed I was getting less than half throttle, all measured from the driver's seat. Earlier systems had a Rover round pin socket in the engine bay, and later systems ran the ubiquitous 16 pin socket that manufacturers manage to hide anywhere. Sykes Pickavant covered these quite well with their ACR Advanced Code Reader. They originally did individual 'pods' for different systems, which developed into a programmable MAP (Multiple Application Pod) which should cover your system. It transformed into the SPi. Something suitable should be available on line for not much. As diagnostics improved, you couldn't give away old scanners. If you want advice on pods and leads, just shout, Peter

I have a prt. As far as I can tell the system is bled properly. The heater gets nice and toasty which also helped bring the temps down. Ill check the hoses. I am thinking of feeding the heater out pipe towards the radiator so it is also cooled rather than heading directly back into the engine.

Running mems 2 no diagnostic sockets. I would love an obd2 plug in, it would have saved me a lot of hassle in he past. Was debating buying an aftermarket ecu just so I can get codes (if any are thrown). Emerald is very expensive (£1k including wiring adaptor) and from what I've read wont give much of a performance boost.

My info shows MGF 95-01 with MEMS 2J. There was a crossover to MEMS 3 in 01. The DLC's (Data Link Connectors) often got 'lost' when people were building specials. I even had one customer cut it off as it was a convenient source of ignition live and earth to wire his radio into. Check with the ecu wiring diagram. All you need is ignition live, earth, and a connection to the K-line from the ecu, and a 16 pin DLC off anything from the scrapyard. Do not get confused with EOBD (Enhanced/European On Board Diagnostics) Not always available on pre-2001 cars, and of limited use. You need to access the Rover diagnostics, Peter

How old is the thermostat?

It could be getting stuck, i.e starts to open when needed but never reaches full lift. Easy enough to test in a pot of hot water on the hob.

Neil

Right, here is my list of stupid/sanity check questions:

As you say you have a PRT fitted, are you 100% that the thermostat was replaced with a blank? If not they could be fighting against each other.

Is the right PRT fitted? I think it should be a "grey" one, although my grey one was black. If I remember correctly 82degreesC

If you raise the revs whilst stationary does it drop the water temperature reading? This opens the PRT due to flow rather than temperature. It may be that the temperature rating of the PRT is too high.

I think if you can determine that the PRT opens above 2k rpm, then I think you can assume the water pump is OK.

I'm sure you've gone through much of this already, but always good to double check.

Also, is the PRT plumbed in correctly?

PRT is grey. I cant remember the temp it opens at. Purchased it many years back but the car was off the road for many years, but yeah it's basically new.

I did test the thermo before putting it in so I was confident in the plumping at the time. As you say might be worth double checking it it's been so long. If it was the wrong way around I assume it would take ages to warm up which isnt what I'm seeing.

I removed the thermostat rear of engine myself and put a blinking plate in so it is definately empty and not blocked.

Water pump timing belt etc are like the thermostat. Old in age but new with regards to actual useage time. Might be worth removing the pump and checking that the fins arent corroded.

Sorry it's taken so long to come back on this thread I've not had the time with work to do anything further on the car until now.

Temperatures I am convinced are actually OK. I found that the temp sensor was fluctuating with the various electronics turned on and off so there is some sort of underlying electrical / ground issue. For instance, when the main beams are activated the temp jumps 10C to 100C and immediately falls back to 90 when turned off again!

Cant get my head around the sputtering on deceleration and poor performance. I cleaned everything out (fuel lines, injectors) and there was no change. Rechecked compression is OK. I've placed an order for a fuel pressure gauge and will have a look if the pump is OK.

What about sensors? Could the map / O2 sensors cause such issues?

Re the sputtering question, I'll respond with a few questions...
Does it have a catalyst? If so is it a standard Rover type or an aftermarket "sports" cat? O2 sensors before and after or just one?

If you do have a cat if you remove and gently shake can you hear anything moving around inside? It is not uncommon for the matrix to break down and block the flow path. A friend with a sports cat had the whole centre section detach and turn through 90 degrees completely blocking the exhaust! The OEM ceramic cores tend to break into bits and rattle around so usually only partially block.

With O2 sensor failures the ECU tends towards running rich as a default so if they've gone wrong you'd be getting a black sooty exhaust and possibly fouled plugs and someone following you would be smelling the richness.

There is no CAT on this and just the one sensor. It's the normal exhaust nothing fancy. No black soot or smell of fuel. Plugs looked OK, they were all uniform, slight grey colour I guess but unfortunately I didnt think to take a photo. The exhaust kicks out a bit of water until its warm but that's normal I guess?

I tried disconnecting the o2 plug for the sensor and the engine note didnt change.

I've purchased some "dry fuel" additive incase theres any water in the tank. With all that rust I suppose that could be a possibility...?

Only other thing I can think is timing. I'll check it again

Unlikely an O2 sensor would cause poor performance. Map sensor perhaps, however before you look at anything electronic check:
- Ignition timing
- manifold vacuum
- valve timing
- compression test
- fuel pressure (Including under load)

Also do a quick battery check and see if you are getting 14/15v when running to make sure charging circuit ok.