Running hot?

Boxwolf · Post by **Boxwolf** » Mon Apr 06, 2009 6:27 pm

My recently aqquired TXD seems to have a habit of kicking in one (and sometimes both) of the radiator cooling fans when idling after driving. Is this normal on the 1.7TD engine or should I be looking at flushing the radiator?

I have not had either of the temperature warning lights illuminate, so I'm guessing if anything is wrong its not serious but it does bring the fans in a lot more than my old car (1.9d 306)

I stuck my hand behind the rad today top and underneath to check for cold spots (how much cooler is a cold spot normally?) but all the parts I could reach seemed fairly hot.

ken newbold · Post by **ken newbold** » Mon Apr 06, 2009 9:02 pm

Cool spots are usually cold in my experiance.

Might pay you to take the rad off, flush it out and also blast through the vains as it could be suffering from air flow problems. You wanna get it sorted before the weather gets warm.

Boxwolf · Post by **Boxwolf** » Tue Apr 07, 2009 4:13 pm

It has occurred to me the coolant level may be too low, I have looked at it and its about 1cm (maybe less) over the middle line of the expansion tank. There are no min/max indicators on the tank as far as I can see and I cant find anything online which says how full the tank needs to be.

I'm not confident to try and pull the radiator off, as i'm not very good mechanically and messing with something that prevents the engine from blowing its head gasket when I dont know what i'm doing doesnt seem like a good idea :S

On Tim's advice I'm going to crank open the bleed screw slightly today and see if theres any air sitting at the top of the rad.

ken newbold · Post by **ken newbold** » Tue Apr 07, 2009 4:25 pm

The water in the tank should be about half way, your's sounds about right.

You could try jetting the rad in situ by going in through the grille at the front and blasting the muck out from there.

Boxwolf · Post by **Boxwolf** » Tue Apr 07, 2009 5:01 pm

Okay, I just checked it with the engine cold and its just below the little plastic rectangle in the middle of the tank. I'll add a bit so its above this. I decided not to open the bleed screw until I was sure the level wasnt too low.

According to the service document, the coolant was changed in november but its a little cloudy and smells like bad armpit. I hope it doesnt need changing cause thats not something I can do myself.

Jetting the rad sounds like an idea, but i'll need to take it to a fuel station with a pressure washer cause I dont have one. Will the fans mind getting wet?

ken newbold · Post by **ken newbold** » Tue Apr 07, 2009 5:54 pm

No, they love it

Post by **Tim Leech** » Tue Apr 07, 2009 6:01 pm

Whilst your at it I would give the intercooler a good balst as I found doing that gave my TZD more oomph.

DLM · Post by **DLM** » Tue Apr 07, 2009 6:29 pm

I'm going to crank open the bleed screw slightly today and see if theres any air sitting at the top of the rad.

If there is air sitting at the top of the rad, expect a cold spot as Ken says. Doesn't sound like that, though. The newish coolant may have picked up any traces of crud left in the system on refill if it wasn't also flushed at the time - maybe even if it was.

Only worry if the water is VERY rusty (this is why blue/green antifreeze is preferable to avoid confusion).

So long as the radiator hose is a bit soft and squeezable after the car's been left overnight, and there isn't much pressure if you remove the filler cap in the same circumstances, you should just continue to monitor that fan cut-in after doing what Ken advises.

Boxwolf · Post by **Boxwolf** » Tue Apr 07, 2009 7:09 pm

Just took it for a short drive after topping the coolant up a bit and bleeding the rad, used the turbo plenty and then parked it back up. I left the engine idling and took a note of the time, and it was four minutes before the fans came in to cool the engine off. It doesnt seem to start the fans if left to idle without driving first as far as i know, and it seems less inclined to cool itself if I drive without the turbo.

I'll check the radiator hose and how much pressure there is under the filler cap tomorrow morning if i remember.

Any guidelines for jetwashing the radiator in terms of avoiding electrical bits etc?

DLM · Post by **DLM** » Tue Apr 07, 2009 10:06 pm

Just took it for a short drive after topping the coolant up a bit and bleeding the rad, used the turbo plenty and then parked it back up. I left the engine idling and took a note of the time, and it was four minutes before the fans came in to cool the engine off.

To be honest, that sounds par-ish for the course - you're getting up to operating temperature with the higher revs used and any car creeps up from that point temp-wise if then stopped and idling for a while. It's the extra revs that raise the temperature, not the turbo as such.

Do you have a fairly heavy right foot? I personally don't take let the rev counter go up too far when accelerating on a BX turbodiesel as a change up takes you quickly back into the 2000rpm-upward band where there's maximum torque and best acceleration. Best driving style may well differ from the 306 as the turbo fitted there may well operate over a slightly different range. Don't know...

It doesnt seem to start the fans if left to idle without driving first as far as i know, and it seems less inclined to cool itself if I drive without the turbo.

As above. Lower revs, less going on. Unless you're climbing serious hills slowly....

Any guidelines for jetwashing the radiator in terms of avoiding electrical bits etc?

Erm....avoiding the electrical bits if it worries you. Directing the jet inwards toward the centre-line of the car and not jetting towards the sides.

On a different-model BX I might advise to jetwash from behind the rad but as you have to unpack the air pipes to get there on a BX TD it would be dangerous for the engine as one little drop of water bouncing back into the air intake somewhere could do a lot of damage. Bang goes that engine.

Check the intake system leading from air filter to turbo intake is tightly secured anyway to be safe, if what I've just said bothers you.

The mini-grille in front of the bonnet could come off for access if you've got the right torx bits for the the 2 or 3 screws, but you might find yourself driving away without it on afterwards: it can prove troublesome to get back on until you figure out the origami with the rubber flaps on either side of it and exactly where it sits.

I'd give the intercooler a miss for now - much better to get to a point where you have full confidence in the cooling system before thinking of extra go. It cools air going into the turbo, not the engine.

I personally clean it out off-car on a warm day so it can be jetted or hosed from both sides, drying it thoroughly before replacing. But then only if it's obviously cacked-up. On-car I'd do it if steam-cleaning the engine bay rather than a fierce jetwash under the bonnet.

I'll check the radiator hose and how much pressure there is under the filler cap tomorrow morning if i remember.

Do it sometime - it's a check that the cooling system isn't over-pressurising - normally as a consequence of head-gasket nasties, which I don't think you have (unless you're redlining the rev counter regularly).

Boxwolf · Post by **Boxwolf** » Wed Apr 08, 2009 10:04 am

Okay, I checked this morning and the hose was soft and no pressure under the filler cap at all.

My right foot is sometimes heavy but I usually change up at just over 3k rpm. The turbo in my TXD seems to be just starting to come in at 2k and at its peak about 3k. My 306 didnt have a turbo, this is the first TD car I have owned.

I'll probably take it for a radiator jet wash today later on, bit concerned about getting water in the air intake though, which has, incidentally, come apart from the bit of plastic its normally attached to (plastic snapped) and i'm not sure if that makes it more risky or less cause i'm not entirely sure where it gets its air from.

Boxwolf · Post by **Boxwolf** » Wed Apr 08, 2009 3:03 pm

I took the car down to a jet wash today and sprayed lots of water into the bottom grille, I think most of it went down under the car though. I wasnt sure about spraying into the top grille as that looks like where the car gets its air and as mentioned before didnt want to get water in the air intake. I dont know how much water managed to reach the radiator but I hope its cleaned it a bit at least. Engine gave a brief blast of one of the fans for about a second when I parked at home and left it running for 3 or 4 minutes.

Correction to earlier post, I usually change below 3k unless I'm after a nice boost from the turbo.

Boxwolf · Post by **Boxwolf** » Mon Jun 29, 2009 7:12 pm

Update on this, I have read somewhere on here that both fans operate on low speed and high, but only one of my fans operates on low which is likely causing the temperature to creep up during idle until the car needs to use the high speed (which is quite noisy on my car)

is there a way to test/fix this issue?

Jaba · Post by **Jaba** » Tue Jun 30, 2009 1:44 am

A good first step would be to either run 12v volts to the failing fan to see if it will spin - or just swap them over and see if the fault moves with the fan. You will then know if you have an electrical fault or a duff fan. The connectors are just behind the bumper and do get corroded.

PRM has posted a pic of the wiring diagram in another thread of TB2's overheating.

Boxwolf · Post by **Boxwolf** » Tue Jun 30, 2009 7:35 pm

Can the wires/fans be accessed without removing the bumper, and if not how difficult is the bumper to pull off?