Typical sod’s law when fault finding: either you induce a new fault as he did, or there are coincidentally two faults running side by side, where fixing one doesn’t solve the issue… Nevertheless, there would never be such a reward if it were that easy!
So here I am, with another couple of issues, as nothing runs smoothly! One of the queries is about the cooling system, so can move the post if need be, but thought it’d be alright to keep them all in the same place as prior issues can be seen above.
So the issue is that my radiator seems to get very hot, so much so that it starts to steam. Now, I’ve spotted a leak at the bottom of the rad., so I’m thinking maybe it’s just normal for it to get hot enough for the water to evaporate when it leaks on to the surface. I also understand that any leaks can lead to the system over heating, due to lower pressure etc. When it gets hot, the lower rad hose is cold and of course the top hose is hot, so I’m thinking a potential blockage. The fan, however, doesn’t kick in at all, despite shorting in the diag box to which it DOES come on, and the relay clicks. I’ve also switched the water temp. sensor at the back of the engine for my previously known working one.
I suspected that maybe, as the water doesn’t seem to be circulating very well, the sensor is reading that the water is still cold, therefore not bringing in the fan, but the gauge temp sensor right next to it reads a constant 2 o’clock (slightly higher than when I had my previous engine, but maybe due to the leak…) so it must be getting at least some hot water.
My aim is to change the rad. and see if this sorts the issue. But the main question is, could it be possible that the bad circulation is allowing not-so-hot water (potentially just being heated up through convection at the back of the engine) to sit where the sensor is, not get much hotter as it’s not moving through the engine, and keep the fan from coming on as it’s not sensing a real temp increase?
I’m wondering if the bad circulation caused my last water pump to fail, therefore allowing certain parts of the engine to get extremely hot without water flow to show this through the sensor, which could have been why the water pump completely failed and the system sprang several leaks.
Sorry for the length, thanks for any help.
Hi J,
Have you considered that the thermostat may not be opening?
I’d get the radiator changed then review it, do one thing at a time. No point trying to tackle other faults when you have one staring you in the face. Water on the outside of a radiator can steam for ages, it accumulates in between the fins.
1 Like
It’s a brand new genuine thermostat, so hopefully not, but items can be faulty I guess. Makes sense to tackle one thing at a time, it might just solve all my problems. I’m just doing that thing where I keep over thinking things! Cheers for the replies.
So, new radiator fitted, bled all the air out of the system, fan still not kicking in! Both top and bottom are now getting hot, with thermostat seeming to open (as the water level dropped after 5-10 mins of running, and the heater core hoses were warmed up nicely. It would seem the water pump works, as the level drops when I rev the engine, and you can kinda see the water flowing when you look through the rad cap opening. The only thing I can think of is that I’ve removed the air con system, and currently have the plugs for that hanging down in the engine bay. Is there any part of the air con wiring system that needed to be linked out for normal fan function, such as the grounds?
Besides this, there is a deep "pop pop…pop…pop…pop pop sound coming from the engine itself when you put an ear to the head. The noise speeds up when the engine revs up too, with this characteristic being mimicked through the exhaust system, I dont know if any of this is linked, but they are the two problems that I’m left with. Cheers, James.
Does the fan work if you ground the TFA terminal in the Diagnostic port under the bonnet? You are waiting long enough for it to kick in aren’t you?
The pop pop you describe does sound like a leaky valve from your description…
Yeh, the fan does come on when I short them. I feel like it’s long enough, cus everything gets very hot. A good 20 mins of the engine running.
I did a compression test with great results (180 psi across all cylinders), would that have detected a leaky valve?
Try holding the engine revs up at a steady 2500 rpm for a bit when the engine is warm and see if that switches the fan. Obviously keep an eye on the temp gauge though.
I’ll give that a go, thanks. I’ve also realised that the AC fan never came on when I pressed the button, so I’m wondering if someone had played around with it before. However, the AC has been ripped out now, so I wonder if something is amiss. I’ll have to check some voltages and see what’s going on.
Not sure what this means, but I remember when we connected everything back up in the engine bay, these lugs weren’t attached to anything, but when we connected then to ground, where they were before, there were a few sparks and the fan stopped and started a couple of times. I’ve tried moving these around since, but nothing at all now.
Sadly no luck with the fan still, after the engine got very hot and some revs. Found a small leak at one of the heater core hoses, which will be my next fix. The bottom radiator hose to engine section (shown in the picture below)will not heat up at all, but every other water hose gets hot. Should I be concerned about poor circulation from the waterpump? I have thought about the fact that maybe it’s just not getting hot enough for the fan to kick in, but before the engine change it was kicking in way before this…
Airlock??
I guess it could be, due to the leak…
Air locks are normal when draining and refilling with coolant
If the aircon has been removed but the AC fan and wiring are still there, then you can usually get that fan to run when you press the AC button if you make two links to bypass the previous gas pressure switch and icing switch. (Those were cutouts to stop the AC if the refrigerant pressure was low or if the evaporator iced up. They just break the link from the AC button to the ECU.)
The pressure switch was on the pipe which ran from the condenser around the radiator and along the offside chassis leg, just a short way back from the rad (wires are probably green/black, black/blue). The icing switch was in the right hand side of the evaporator, behind the glovebox (black/blue, green/red). If you can find those dangling pairs of wires and link them together, the AC fan should run when you press the AC button.
Thanks Martin, I’ll get on to that. At least if I can get the fan running, I can see how it affects the temperature of the engine as a temporary check for diagnosing the (potential) overheating issue.
On another note, since changing the original '93 inlet manifold (pictured first below) to the newer '97 inlet manifold designed for EGR valve, I cant work out where to put the vacuum hoses to work most effectively. Not sure if there is a done way, or if they simply aren’t compatible with each other. I’ve colour coded them incase anyone is able to help?
Thanks for all suggestions with my on-going log of faults =)
Update and follow up question with video link attached:
After disconnecting and reconnecting parts of the cooling fan wiring circuit, along with relays and fuses, the radiator now kicks in. Either I wasnt leaving it long enough, or there was a loose/dirty connection, either way that issue is now sorted.
Just one last thing, which could be the biggest problem is the “pop…pop pop” noise, which is amplified through the air intake. It’s not always on a particular beat, and as I rev slowly it can be heard increasing with the revs to a fast pop. I’ve changed the plugs, tested the coil pack for correct resistance from lead port to port (getting around 10 Ohms), swapped leads (admittedly with an unknown good/bad), and blanked off egr vacuum ports, but still get the same popping, and occasional misfiring under acceleration (not under load, just on the drive). It has also been compressionon tested with good results. Maybe my forms of diagnosis haven’t been correct or good enough, but any help is appreciated. Link to video of noise: https://youtu.be/376r1z7AxT0
Thank you.