|
colin4255
Sr. Member
Posts: 119
|
|
« Reply #16 on: January 24, 2011, 02:01:17 pm » |
|
If we are to assume radiator, heater matrixes, expansion tank and cap and all the hoses are OK and in good condition, then either you have been very unlucky and got two thermostats that don't work properly, OR your head gasket is leaking - they don't always go with a bang and in a cloud of steam straight away, they can leak for ages first - this would explain the high pressure, it could be coming from a leaking head gasket. No easy way to tell apart from take the head off though anf then you'll have to replace the gasket in any case!!
Try the themostat first. I am not sure about new ones, but a few years back, you could actually test a thermostat, by hanging it using string, immersed in a pan of boiling water. If it worked, you'd actually see it open. Maybe worth a try once you have taken the thing out of the car??
|
|
|
Logged
|
|
|
|
|
|
|
|
|
|
roy4matra
YaBB God
Posts: 1200
|
|
« Reply #23 on: January 28, 2011, 05:25:00 pm » |
|
Hi guys Back to the drawing board... This morning even before I turned the engine over i took the cap of the expansion tank and the pressure threw the water out ? Does anyone have any ideas why this is happening.. I'm sorry to say but this sounds like you have a head gasket blown at best, or a crack at worst. To retain sufficient pressure over night to blow out coolant there must have been a lot of pressure in the system and that is not just the normal 1-2 bar created by the system being sealed and the coolant being heated. The expanded hoses that you mentioned earlier also point to the over-pressure caused by the engine pressurising the cooling system, and the final proof is the heater blowing cold - as the engine blows gases into the coolant, this goes initially to the highest point in the system which are the matricies. The fact that the heater is often cold right from the start is that the engine gases are already there from the previous run, so they don't get the warm coolant to work correctly. Although you have had a gasket done a couple of years back, you may have caused it to blow again by getting it too hot (you said you switched it off when it reached the red but that is too late - the top of an engine gets even hotter just after switching off as the heat rises) or it may be that originally it wasn't a gasket but the start of a crack, and since then it has been slowly getting worse. This does not sound like a problem with the thermostat at all, particularly since you have now fitted two new ones, and I would not waste time with that at this time. A compression check should be the first test, and the engine should be hot (which is when the gasket or crack opens up) or possibly a block coolant test - this is a fluid that changes colour in the presence of engine gases in the coolant. Tightening down the head bolts will not do anything even assuming you can get at them all, and if you do have a crack then that is another reason why tightening the head bolts would be a waste of time. To remove the head on these engine means removing the engine, and that really means having a ramp since you have to lift the chassis away from the engine. The garages have an engine dolly, and once all the bolts, electrics connections, pipes etc. are off or apart, the engine sits on this whilst the mountings are undone, and then the chassis is lifted up, leaving the engine on the dolly. To do this at home with normal DIY tools is not really a sensible proposition. Roy
|
|
« Last Edit: January 28, 2011, 05:32:09 pm by roy4matra »
|
Logged
|
|
|
|
|
|
|
jack daniels
Sr. Member
Posts: 132
|
|
« Reply #27 on: February 03, 2011, 12:23:58 pm » |
|
that is a good point Colin. I dont know if that detail is in the average workshop manual, but one should allways check in a stud hole one way or another before puting the stud in. I use a least a vernier caliper to measure the depth, and take a look with a light, if that's possible. I measure the stud length before putting it in and again after its in to keep control over where they are. If you have another bolt to hand with the same thread but cut to a smaller dia you can even just run that in by hand to check that the thread is deep enough and not just the hole itself. There could be swarf, loctite, or fluid in there. The thread could even be damaged. An air pistol is ok but abrasive crap could come flying out, so its a good idea to at least cover the pistol and the hole with a rag. If there is lubricant in there, it could easily cause hydraulic lock for sure.
|
|
|
Logged
|
Espace, Grand (magnifique, formidable, grandiose, considérable, noble, ample) III 2002 JE02 F4R DP0 2.0L 16v auto
|
|
|
|
|