running cold on the M way
Discussion
been out for a 100 mile trip today in the griff and for once in my life i have been cold in the cab!!
The temp was reading about 60 and the heaters blew cold most of the way there and back doing about 70/80 mph.
Is this usual???
Before anyone asks the coolant is topped up and the stat seems to kick in OK.
The temp was reading about 60 and the heaters blew cold most of the way there and back doing about 70/80 mph.
Is this usual???
Before anyone asks the coolant is topped up and the stat seems to kick in OK.
david beer said:
Sounds like the water stat is open all the time, it should "kick out"/ open, only when the engine is up to temperature. That will depend on the stat fitted, 72, open at that point, 82,88 etc. Do not confuse with the post just below !
Feeling the radiator at warm up doesnt support this theory, sorry david.
I can feel the stat open when holding the hoses when the temp comes up.
Just had my stat replaced because of the same concern. Prior to replacement I am quite confident the stat was sticking open as there was a very gradual rise to 50 degrees on the coolant temp guage and the in-flow pipe to the rad warmed slowly.
With the new stat installed, the temp guage stays way off the scale to the left and after a few minutes moves quickly to 50ish suggesting the stat is opening up as one would expect ... but even so on a 70mph motorway cruise the temp dipped from 70 degrees back to about 60 with the external air temp probably around 3 or 4 degrees. So, given i'm pretty sure the stat is now sorted, 60 on the guauge no longer worries me too much.
With the new stat installed, the temp guage stays way off the scale to the left and after a few minutes moves quickly to 50ish suggesting the stat is opening up as one would expect ... but even so on a 70mph motorway cruise the temp dipped from 70 degrees back to about 60 with the external air temp probably around 3 or 4 degrees. So, given i'm pretty sure the stat is now sorted, 60 on the guauge no longer worries me too much.
The rad should remain cold until the water sat opens, at what temp is this ? The inlet pipe is the one to hold(passengers side), if you hold the outlet,the drivers side, it will get warm early as the heater outlet will warm it. If the inlet hose stays cold until the stat opens and the temp is 80, if you see 60 on the motorway, its not the engine running cold, its the sender getting cold.
david beer said:
if you hold the outlet,the drivers side, it will get warm early as the heater outlet will warm it.
The heater is normally supplied from the back of the inlet manifold water jacket, and the return goes to the water pump inlet. I'd be very surprised to find the heater return connected into the top hose. If the top hose gets warm before the engine reaches the stat opening temperature, this indicates that the stat is leaking/faulty. It's common to drill a small hole in the state to help it bleed, and that is enough to warm the top hose. This leakage has negligeable effect most of the time, but cruising in extremely cold conditions with the engine lightly loaded even this trickle can give you too much cooling.
The original stat designs produce a massive pressure across the stat when its closed, so it's sensitive to the tiniest leak. I used to see this effect with the standard (not drilled) 82 stat, which would leak enough to pull the engine temperature down to 60 degrees in really cold weather. Since I replaced this with an entry stat which is hermetically sealed until it opens, the engine temperature on a cruise is rock steady regardless of the outside temperature.
This is on a V8S which has the ECU and gauge temperature sender both straight into the water jacket at the front of the inlet manifold. If you've got the senders fitted remotely out of the main water flow then it's possible for these to under-read in cold conditions, which will make the engine temperature look even lower than it is.
Hi Peter
seems we are alone on this one now ! I had to read my post again just to make sure.The heater outlet goes to the rad outlet hose which then as you say goes to the water pump, this of course being the bottom hose. I could never understand why my guage read 60-70 on a cold day, i knew my stat was 88, moving to the sender on top of the head, next to the ECU sender cured this, i guess thats the one your guage uses ?
seems we are alone on this one now ! I had to read my post again just to make sure.The heater outlet goes to the rad outlet hose which then as you say goes to the water pump, this of course being the bottom hose. I could never understand why my guage read 60-70 on a cold day, i knew my stat was 88, moving to the sender on top of the head, next to the ECU sender cured this, i guess thats the one your guage uses ?
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