Does water normally boil on the outside of the headgasket ?

[stopping]

I noticed today after firing up the engine that water was boiling off the surface of the head gasket/ head (like bubbling not just steam). I hope this just a precaution and all your diesels out there do this. The system was bled well, there was flow to the heater and no air in the system... the rad was warm.

I have yet to drive it with it's new head gasket and want to avoid unnecessary damage.

Thanks in advance for any advice.

[Dirtrag2]

Uhhh, where is the water comming from  :?:

if it's rainwater or something, it will definately evaporate quickly on the head but boil? i don't think it sould get that hot.  on a hot day and hard driving my water temp gauge shows 110 degres celsius.

[stopping]

110 would do it. I put the water there to see how hot it was getting.

[jtanguay]

110C ? just imagine how hot the head is  :shock:

[Dirtrag2]

110c is on a hot day ( 30c+ ) driving hard... normally only 90c water temp.
head should not get much hotter than the water going thru it, but i may be wrong  :oops:

[jtanguay]

110c is on a hot day ( 30c+ ) driving hard... normally only 90c water temp.
head should not get much hotter than the water going thru it, but i may be wrong  :oops:

well if you've recently flushed the coolant, the head temps should be about 10-30C more (even more from a really hard run) than the coolant... deposits/buildup etc. will only increase the difference.  products like water wetter and using special coolants will help the heat transfer greatly though.

110C is wayyyyyyyyyy too high IMO...  but the temp gauges have been known to be off...  you're getting awfully close to blown head gasket territory there.  mix those temps with a good hill climb and whamo!  something is bound to give.. either HG, coolant hose, or something else...  

i think your rad fan might be broken, or the thermo-switch in the rad.

[Dakotakid]

Hey wait...did you fill the block through the top radiator hose or are you baking air (air locked)

[stopping]

thanks for responding so fast.

Filling through the top head hose is a good idea and new to me. I will try it. I am getting (seemingly constant) flow to the heater from the head. All should be good... I am a bit paranoid I guess.

I have a bleeder valve at the top radiator hose so that should allow the water to fill the head and block.

New observation: I don't think the head on my engine is getting very hot but the head gasket and the lower part of the head are. There was some water pooled in the injector bosses and that never even got hot enough to steam and the water remains there. The water pooled by the (2 notch) tab does boil... really!

Merci a jtanguey
10-30 deg C higher is good to know about. I will run it carfullly down the  road now and report back with results from a digi thermometer (outside the block/ head).

[stopping]

ok it seems normal... I still don't know but water temps are 88 when the head gasket is 104 deg.C. outside temp is 23-25 degC. The engine is circulating through the rad and the heater core. I was shutting down before the lower part of the head got to 100 (the water was only at 80-85 and the thermo did not open.

That's what is surprising.... I would have thought the aluminium head and the water in it would equalize the temperature more than that. That's for your help but if you want to confirm my suspicions please do.

Maybe timing is to advanced or there is too much fuel. It can't be by much if at all.

[stopping]

This about my Vanagon and it is still not right. In fact I am unable to drive it now. Same situation. The van runs smooth and steady at idle, the water circulates normally (ie: rad hot and heater hot) as soon as you make it work it over heats, the water seems to stop circulating and it boils the water in the engine at the same time the rad goes from hot to cold.

I should say I just replaced the water pump with a new stamped steel style pump. Seems to be marginally better for flow and pressure.
 
The flow in the rad is not reversed according to Bentley and logic.

I am running water not coolant until I figure this out.

What can it be?

I have been dealing with this for too long. There is no head gasket/ cracked block-head leak I know because as I said I have a pressure gauge I can watch.

Some voodoo air lock I just can't get out?

Timing way too advanced?

Something very wrong with the pump?

It has been smoking a bit at idle but it seems to clear up when you drive it.


Paying my dues.

[jimfoo]

Water boils at a much cooler temp. You should be running coolant as you are now getting vapor pockets in the head, and possibly warping it. Did you put in a new thermostat and verify what temp it opens at? Radiator isn't clogged? Fan works? Advanced timing will make the engine run hotter. Have you messed with the fuel screw? More boost will help it run cooler as well.

[stopping]

Thermos were tested. I am now running (trying to run) with a Saab thermostat that opens at the same rate as the VW fully blocks the by-pass and allows more cool water to pass when it is open fully due to a larger orifice.

The fan cycles normally when still and at idle (low fan on 94 C off at 86-88 C) but over heats the moment you make it work.... I am talking about 1000ft down the road and the needle is showing 100 deg+ and the engine starts to boil.

I do have a digital thermometer on the outside of the head that gives me temps that sometimes conflict with the temp gauge in with the instruments. I try not to let the head get above 100 deg C .... but sometimes I have to shut it down if it gets to 105.

The system should work with water only no glycol... if it doesn't I don't feel like I have found the problem... I know glycol raises boil temps and lowers freezing temp.....I could also run with no thermostat... but I must figure this out.

I really don't think the timing is advanced but if it was how much more heat could I expect to see per half rotational degree or say ....per .005 thou on the pump plunger?

What is the normal difference in temp between the out side of the pre-combustion chambers and the cooler top of the head?

[jtanguay]

have you done an engine flush? like i mean do a really good flush!

[stopping]

About the engine flush... I tried when the head was off to force water through every channel of the block so it would remove and rust/ crud blocking the passages.... I forgot to do the head though. And, yes I did do several flushes before that but all i have had is a garden hose... what i want is a fire hose!.. i have been plotting how to get the head out hose connected to a barrel on the roof.... hey maybe i should drive to newfoundland with a barrel of cold water on my roo!....just like an old steamer!

Tomorrow I will going fishing for lodged anything in the pipes running to the front and trying to blast debris from the engine with the help of the local FD.

[Vincent Waldon]

Isn't there a specific Vanagon coolant air-bubble procedure that involves jacking up one wheel or the front.... I have a vague memory of something along those lines  :?

There's a diesel Vanagon specific forum over at www.vwdieselparts.com... those boys may be able to help.  I took a quick peek... some overheating posts mention "bleeding procedure" and some thoughts about differences in the cooling reservoirs and hoses between various model years.

(edit... just realized this is a Stopping post... you know *all* about that forum already !) :oops: