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Post by rwelfare on Nov 29, 2007 23:29:06 GMT
Going to change the thermostat and coolant on my megamile '93 405 GLDT estate this weekend, along with a service. Seems to be a bit of pressure in the system and the heater doesn't get very hot (in stark contrast to my '94 saloon, which is fine in both respects - touch wood) - so I'm hoping that it's not a head gasket issue, but we'll see...
Anyway - once I have drained, flushed and reverse flushed the waterways, what's the best method to bleed the cooling system? I've read that there is a drain plug for the cylinder block - can anyone tell me where it is?
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Post by Donaldiesel on Dec 1, 2007 12:50:27 GMT
If you are going to throughly flush the cooling system, it shouldn't be necessary to drain the block separately. just remove the bottom hose from the rad. The heater control must be in the 'hot' position. The heater may not be getting hot due to an air lock, clogged matrix or seized valve. If you are able to disconnect the heater hoses from the back of the engine (tricky), flushing the heater directly may help.
When refilling, open the bleed screws. (Check your manual to see where they are). Open them again after running the engine to make sure all the air has been released. This is important. Air locks in the cylinder head cause hot spots and damage. Never use plain water without antifreeze or the inside of the engine will corrode badly.
What is this 'bit of pressure' you refer to? Is it more than the normal coolant pressure in a hot engine? I suggest you get a coolant combustion gas analysis before spending time on the above. Any garage can do this in a few minutes.
Regards,
Donaldiesel
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Post by rwelfare on Dec 1, 2007 17:25:45 GMT
Thanks Donaldiesel. I released the bottom hose and thermostat housing and gave both rad and block a thorough flush through, after putting in some flushing agent and running up to temp. Didn't try the heater hoses though.
The Haynes manual gives some positions for bleed valves but I couldn't find any in the given places - only the one on the nearside edge of the rad (which only opened a 1/4 turn - is this right?). I rigged up a 'header tank' with a good seal on the radiator filler and put in a 50/50 mix of distilled water and antifreeze, holding the car at 1500rpm until the rad fan had kicked in and out three times, topping up the header when the level dropped. Took about 6 or 7 ltrs which is about right per Haynes.
There were a lot of air bubbles initially but these did subside, and it now seems rock solid - after another 5-10 min run there seemed no more pressure on opening the rad cap than my saloon. Didn't have enough chance to see if the heater got hot - I couldn't change the thermostat as I was sent the wrong one (too big), but I suspect that my control cable may have stretched over time, as the fan speed slider is slower to respond than my lower-mileage saloon, if that makes sense!
Gas sniffer in the rad is a good tip, I will keep an eye on the car first and then try it if it's still losing coolant. There was no oil in the drained coolant, or coolant in the oil though (as I did a full service today as well).
One more question re. a seized heater valve - would this mean the interior temp is constant no matter where the temp slider position is set? There's currently a definite difference between cold and hot - it's just that 'hot' is merely 'lukewarm'!
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Post by rwelfare on Dec 2, 2007 15:26:29 GMT
A quick update - dodged the rain and wind earlier to try and sort out my rear doors. In the meantime, let the car idle for about 10-15min. Temp gauge didn't do it's usual tricks (moving to the edge of the hatched marks at the bottom of the scale, then plummeting back down, only to jump up to 85) but actually began to creep up towards 75 normally, and lo and behold there's now (a bit of) heat from the vents!
OK, not as toasty as my saloon - which develops searing heat pretty quickly, although that one's temp gauge rarely goes above 75 - but getting there. Have to try it on a run.
Best thing of all was that there was no pressure from the rad cap when opened straight after the engine was shut off.
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Post by Donaldiesel on Dec 3, 2007 7:25:32 GMT
Well done! - Sounds like a through job and you got it sorted. Your hearer matrix is probably a bit clogged inside if it still dosnt get properly hot. You seem to have eliminated all air locks.
Donaldiesel
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Post by rwelfare on Dec 3, 2007 18:59:50 GMT
Ah right, thanks. I will make sure I use the same method when I change the antifreeze on the saloon in a few weeks. I can confirm a cut-down 1.5L Evian bottle makes a good header tank - it's a very tight seal on the radiator inlet ;D
By the way, is red antifreeze OK with these engines? I made sure there were no traces of the original (blue - well, it used to be blue - not much strength left in it!) stuff before I put the new lot in.
How easy is it to get the heater hoses off by the way? I spied some of those irritating spring clips - I had enough trouble with my molegrips on the one attached to the hose at the thermostat housing, I don't fancy dangling over the front wing trying to get at them!
Final question - do non-a/c Phase 2s use a pollen filter? It's dark so I can't check under the plastic panel over the nearside scuttle.
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Post by Donaldiesel on Dec 10, 2007 12:24:53 GMT
On the technical forum 'Beegee' advised against using red antifreeze, though he didnt say why. General rule is to never mix the different types as you can get undesireable chemical reactions and loss of corrosion protection. XUD engine has iron block and aluminium head. It must be protected against internal corrosion. The colour of antifreeze is not an absolute indicator of the type. Always read the label to check. Orange is generally a long life type and can only be used if the system is throughly flushed of the old stuff first. I think red is a Toyota gimmick and is normal antifreeze with a red die.
For years I used Mono Propylene Glycol which is non toxic. However, I can no longer buy this. I'd be interested to know why it has been discontinued. Normal antifreeze is Mono Ethylene Glycol and higly toxic. Many domestic pets are killed each year because they can't resist the sweet taste. Please make sure spills are cleaned up.
I agree about the 'irritating spring clips'. I cut them off and fit worm drive type. Squirt some waxoyl on the worm thread so it still works next time. Dont know about pollen filter.
Regards,
Donaldiesel
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Post by rwelfare on Dec 12, 2007 22:57:24 GMT
Thanks Donaldiesel, since the last post I bought a 1994 405 brochure which tells me all models have a pollen filter, so I've order a couple from Bosch.
The anti-freeze I have is the Long Life stuff from Halfords, which is red. I've heard that too strong a mix can be bad for head gaskets. I went for a 50:50 mix, perhaps a little stronger. I will keep an eye on it. Pretty sure this still is the non-Ethylene stuff. I have two cats so made sure I hosed the driveway well after completion of the job.
Think I will leave the clips for the time being - I'm more concerned about the twist connectors for the hoses going into the rad, just couldn't shift them! (Bottom hose had a worm drive clip). Still, the rad looks OK externally and is holding water so it will do for now.
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