boiling over again :( vn

[cliff_canon]

poor little thing is getting hot again... noticed coolant boling out of cap when hot and trickles when just started. is it boiling cause the engine getting hot or can the whole cooling system be thrown of by a bad radiator cap. does a raditor need to have complete pressure sealed to work properlly. i ve check flow from inlet house and i can feel the heat and water flow.
are there caps out there that are better than others bought one from super cheap for 7$ and it leaked more that the old one?

i hear of bleeding air out of system, how is that done?

i havent lost power or anything so i dont think its head gasket, does get sluggish when the engine starts getting hotter and radiator starts boiling over..

any thoughts would be appreciated
cheers

[VNPOWER]

your vn shouldnt have a radiator cap being a 1990 model. you should have two tanks, one on the left of the engine bay "surge tank" and on the right of the engine bay there should be another tank; this is the overflow tank.

[cliff_canon]

maybe someone changed the radiotor cause this one has a cap and a hose on the radiotor neck that goes back into the resevoir tank. im really worried now cause the coolant seemed oily/dirty. just seems to spray everywher from the cap and worse after i stop, just boils out of the cap bit... could it be boiling cause ive lost all the cooling fluid. im gonna try creating my own rubber seal to add arounf the entrance og the raditor hole and tighten the cap position. every mans nightmare... the head gasket

[VNPOWER]

yeah they must have. I donno what you should do. If i were you, id do everything i mentioned in the previous thread over again. It just sounds like your radiator is blocked. One thing you can try is check the colour of your oil and see if the coolent has got in there from a cracked head. The oil would be a weird looking colour.

[cliff_canon]

went and say two mechanics today.. oil looked ok and the coolant looks a little dirty but could be sluge, i showed them how coolant was just pissing out of the cap. they said should be around 135 pressure so one mecahnic sold me a stronger rating cap and so far i think its ok, havent really taken it for a long drive but i did drive around for 15minutes then let in idle in the carport. as soon as the temp gets to a little pass the 3rd notch the fan kicks in and brings the car down to in between quarter and half way. the mechanic was worried about 2 things
1. he was holding the top hose to the radiator and reved the crap out of the car, the radiator cap did not leak, but he reckons by the feel the there was too much pressure comming into the radiator,
2. when the car is on idle it has a regualr miss. like its idling and drops a little and just repeats that rythim.

does the cooling system realy have alot of pressure in it. the wierd thing is it seems someone has replaced the radiator to one with a cap and the vn series 1 apparently didnt hap rad caps. is this becuase the design is lots of pressure in the cooling system and maybe now that i have a cap type im suseptable to the cap giving way every now and then.

I know I will arrange a proper perssure test... im just scared of the result..

any one have any thoughts.

[na3point8]

got news for u guys series 2 vn's came out in november 90 i'm luky enough to own 1

[sk1p]

My 89 Lexcen's radiator has a cap. And yes the series I VN's didnt have a cap the overflow hose hooked up straight to a connector in the radiator. Doesn't matter that it has a cap.. and since the series I didnt have a cap there shouldn't be much of a reason to take it off!

[VpV6]

1. he was holding the top hose to the radiator and reved the crap out of the car, the radiator cap did not leak, but he reckons by the feel the there was too much pressure comming into the radiator

Get it pressure tested with a meter. I wouldnt let anyone rev my car like that. Of course the pressure will be high when your redlining it. But do you drive at 5000RPM all the time???

Some radiator joints will pressure test your radiator for free.

Oh and dont worry if it has a cap and an overflow tank. Someones just replaced your radiator with one from a Series II VN. It will be fine.

[rimz81]

Have you checked the radiator filler neck surface sometimes these push upwards and create a poor seal ,bending the tabs down can often cure this.

[cliff_canon]

second day no leaks and temp doesnt seem to get any higher that 1/2 way and fan comes on just before it gets to half but cruises on just above the 2nd notch. i noticed though that when engine has been running a while i dont get us much crisspy power as when i freshly start it in the mornings. its horrible now im always obsessed on the temp gauge.

[jo_blow56]

Hey,

I have a 1990 VN commodore with the two colling tanks one on eather side and no radiator cap, the main tank on the left (Drivers, Surge) was leaking out quite alot via the cap, took it to a mechanic and found the cap was broken and was told that this is a issue at times with the Series II VN the cap go's in them, the way this is fixed was the right hand tank (Passenger side) was removed and a new cap was put on the left tank, ( A whole cap not the origional with the tubing that ran to the right tank (overfill) because this cap is no longer manufacured. There is no longer any issues and the car stays at a constant low steady temp.

John w

[cliff_canon]

i think .. just maybe she's stable again. I think my problem started when the fan stopped working due to the coolant sensor which is now fixed but thinking back it was when i added coolant to the car via the radiator cap that she just kept boilng over. the thing is this vn series 1 has a radiator cap and a surge tank and a surge tank when the original did not have caps. i have since done a radiator flush/reverse engine flush and also found a cap that was a perfect seal and found the exact position it likes on the neck and i wont be moving it ever again. there seems to be no bleeder in this model so what ive been doing is bleeding the air out via the surge tank by openning the lid slowly when slightly wark unitil the coolant rises and slightly over flows and topping up when cool. the car seems to hover between the second notch and gets to half way and back down to second noth when crusing on a highway. ive been checking the neck for leaks and level each time and im not loosing coolant or boling over any more. so ive learnt that air in the cooling system really does cause havoc.. cause i guess air heats up quicker than water. so just maybe i dont have a gasket issue... fingers crossed after i drive to woolongong and back on the weekend.

[cliff_canon]

passed the test drove around liverpool mid afternoon trafic the temp gauge got to little pass half way was the extreme temp but no boil over or leaks and fan kicks in beautifully, then took it straight back to sydney and of to wolloongong and back to sydney...heeeheeee ran like a baby!!! no green spots anywhere!!!

[sp001in]

I am a qualified mechanic and have the answer to your problem, what you need to do is bleed the system but properly.

you will need a flat head screwdriver, a straight piece of radiator hose approx 30cm long, with a diameter that fits into the top of the radiator with the cap off.

remove radiator cap
place tube into top of radiator hold it down so it seals pretty well
loosen off bleed valve
fill tube with premixed coolant to top of tube
watch the bubbles come out of bleed valve when the stop tighten valve
replace radiator cap

go for quick drive and repeat bleed process once more

the trick here is that the tube allows the bleed valve to utilise a gravity feed and bleeding the system without this tube or something lower than the bleed valve simply adds more air into the system.

let me know how this works for you

[cliff_canon]

the trick here is that the tube allows the bleed valve to utilise a gravity feed and bleeding the system without this tube or something lower than the bleed valve simply adds more air into the system.

let me know how this works for you

hey sp001in how do you think i can bleed it without a bleed valve.. just open the lid of the surge tank? i only have one surge tank and radiator with a cap but still a vn series 1, i dont think they have bleeders..any thoughts?

i cut out two rubber rings out of bike tube and made like a gasket and sealed the lip and the neck of the radiator along with a nice and with tight radiator cap. this seems to have stopped pressure coming out of the radiator cap... i guess if i do have a real problem like head/gasket problem my hoses will blow first! something will have to give! hehe