Revs vs speed vs temp

[Graham L]

As Alex and a couple of others have pointed out theres an optimum fan speed at around 3400 RPM which gives maximim cooling, sounds like I'd be checking your rev counter and oil temp sender Karl. Sounds like you might have been driving a bit too cautiously :mrgreen:

 

[Eeza]

These vans were driven by White Van Man 40 years ago...... :? Enjoy You will never be 100% sure of getting there but just enjoy the ride

 

[creationblue]

My 1776 was built to potentially 'charge it, so if the billet crank or Male pistons ect break then I'm seriously gonna loose faith in humanity! I just run a tacho btw 8)

 

[john the horse]

I don't mate but I've never stopped and not been able to hold the dipstick. The engines were designed to work in far more extreme climates than the UK so I'm not worried. Maybe if I had an expensive engine I would be more concerned but not for my stock 1600. I'm sure in spain it would run hotter but I still wouldn't think that you are pushing the extremes of what it was designed for.

I guess the question could be reversed, how do you know you would of cooked it? Granted the temperature would probably increase but it could well run fine like that.

Youll know if ya cooked it , back from vegas a couple of years back , in hurry dropped the hammer foot burried for an hour. shredded belt no alt light as belt semi present. van stopped. the end. new block, er yes please thanks. ps cheers fro the belt ollie still not give ya that back.

john oh yeah have since fitted gauge and it does my head in up down up down. grr. 55mph all the time with a quick 10 mins pedal to the metal and back to 55 works for me. oh and black insulating tape over that annoying gauge. so drive sensible, with all tin and its fine, remember these buses were not designed to blast along on motorways at 70 and wasnt the m1 only opened in 59, there ya go then.

nag over

jth

 

[Zebedee]

Something weird i found on the way to bugjam last weekend was if i drove with both front windows wound right down the van ran at nearly 10 degrees hotter than when they were shut. :? I assume its disturbing the airflow as it passes along the side of the van heading to the air intake vents.
I also found if i reduced speed to 50mph (from 55-60) the temperature went down by nearly 10 degrees and hitting 70 raised it by 15.

If you can't hold the dipstick after a long run its probably been running at about 120+ degrees.

My VDO worry gauge reads nearly 10 degrees higher than the actual temperature (measured using a £2k digital temperature gauge). At 30 degree outside temperature it sat at 108c on the guage (so about 98c actual) at a constant 55-60MPH.

I fitted the bigger 7 row type4 cooler instead of the stock doghouse 5 row one and it reduced the temperature by about 5-7c.

 

[Matt_B]

Excuse my ignorance here, but why do engines fail at these "high" temperatures? In my, albeit simple mind 120 to 150 degrees isn't that hot for metal and oil, I stick thin sheets of metal in my domestic oven at well over 200 and they don't crack and buckle! Just a thought!

 

[sparkywig]

The oil thins and breaks down, pressure falls, lubrication reduces, causing metal to metal contact.

 

[monkeyvanwestybike]

The oil thins and breaks down, pressure falls, lubrication reduces, causing metal to metal contact.

Followed by massive lack of power/ roaring sound and lots of smoke
as i found out on the M5 once
pulled in hard shoulder and let tick over to cool down a bit :shock:

multigrade phhh! never again

 

[Trikky2]

None of the overheating engine failures I have seen involved problems with lubrication. They failed through valve or piston damage (or both). The only way oil was implicated was where the valve or piston had got so hot it literally burnt the oil off the surface of the valve stems or rings. Unfortunately cooling the oil will not help in such extreem conditions.

The main causes of overheating are incorrect ignition timing, incorrect valve clearances, lean mixture, missing tinware and associated baffles / air directors, loose fanbelt etc. Also, in one case, running with the hoses from the fan housing to the heat exchangers removed and not blocked off.

Another common cause is simply a worn engine, particularly worn valve guides. Worn guides will prevent the valve from seating correctly and hence it can no longer dissipate its heat into the cylinder head via the valve seat. The heat travels up the stem and burns off the oil creating rapid further wear of the guide. This becomes a vicious circle and soon the valve head begins to glow which causes futher overheating through pre ignition.

The mis-seating valve head, now glowing, becomes malleable and gets bent around as it mis seats which results in metal fatigue and the valve head snaps off and goes through the piston, also wrecking the head. Somtimes the valve survives long enough until the piston gets burnt, normally at the edges, which results in a cheaper re build. Hence its vital to check the valve guides if re using a head.