Overheating and coolant "boiling like a kettle" in my reservoir

[Limpy92]

Hey guys, i have quite a few problems with my VS but the main ones are the overheating and steam coming from my head.. Driving on a highway or over 80kph in general it runs fine, the temp gauge happily sits under 1/4 but as soon as i start to do town driving. Stop start, traffic lights anything like that it immediately starts to over heat. Shoots upto H sometimes and pretty much dumps all of my radiator fluid all over the road. I've had a mate look it over and he thinks it's my headgasket, but there's no oil in my water, no water in my oil. There is steam coming from the head itself though. I've been told my thermostat could be stuck in "closed" so i've ordered a new one and hoping that replacing that will fix the problem, but not too sure if i need to replace my headgasket too? Not going to a mechanic going to do everything myself, and money for parts isn't an issue. I just need someone elses 2 cents so i can get a better idea what i'm in for cheers.
-Anthony

 

[wortus]

Blown head gasket is going to cause problems all the time not just when in traffic. Other than the thermostat look to see if your thermo fans are working and then take off the water pump and see if the fins are not corroded away, then check the radiator is not blocked.
When you take the thermostat out put it into a saucepan with a thermometer and see if it opens properly when it should. If it does then it's a good bet it's one of the above I have mentioned so I would then take the water pump off to check before refilling the cooling system.

 

[VPRob]

thermo fans sound like the no.1 suspect from your description. there's a way to test the fan circuit for the VS that I read somewhere on this site recently. I recently found the booster fan was not running on my VP because the connecting plug had a poor connection. The test routine is different on a VP.

 

[K-BAGZ]

Now, I can't stress this enough... it's something so simple but people do not seem to understand.

Before you do any repairs, check for fault codes! Next thing is to pressure test the cooling system and radiator cap when the engine is cold! Doing this procedure will shed a light on any external coolant leaks, eg. radiator and heater hoses, water pump gasket, thermostat gasket, heater valve etc. It can also pinpoint internal coolant leakage, eg cylinder head gasket (bubbles in the radiator filler neck can indicate a blown head gasket).

Your main issue is an overheating problem correct? There are many causes to this issue. I'll start with the simple troubleshooting first.

1. Check your engine oil level. - A low engine oil level can play a huge part in engine overheating problems.

2. Clean your radiator core. - Grab a garden hose and give the radiator a good thorough clean, side to side slowing making your way from top to bottom. Front and back sides too.

3.Check the coolant level. - Now, check the condition of the radiator cap (A pressure test on the radiator cap will maybe show signs of a damaged pressure valve) and check the coolant level at the radiator filler neck. If low, top up with coolant or distilled water until it starts to overflow from the radiator neck and then reinstall the radiator cap. Then fill the coolant reservoir bottle to the full mark also. I'll talk about bleeding the system shortly.

4. Check the cooling system electrical circuit. - Your best friend is a multimeter here.
Fan cut in temperature
Low speed - 104C plus
High speed - 109C plus

Fan cut out temperature
Low speed - minus 100
High speed - minus 105

Cooling Fan Test Procedure.
With the engine cold, turn the ignition on and make the sure the cooling fan isn't rotating. If it doesn't rotate, disconnect the coolant temperature sensor ( The larger sensor under the thermostat housing) and start the engine. After around about 15-20 seconds the cooling fan should start spinning at it's low speed, and after another 5-10 seconds the fan should increase to it's high speed. This check means that the fan circuit works fine. If not, however, you need to check the relays and terminals for continuity as you could possibly have a wiring short or a faulty relay.

5. Check the cooling system components. - First off, the thermostat. Remove the top radiator hose and thermostat housing and then you have access to the thermostat.

Thermostat.
Opening temperature - 90C
Fully open temperature - 106C

Get a saucepan and fill it with water and boil on the stove. Grab the thermostat with a pair of pliers and place it in the saucepan, with the thermostat fully submerged. Then grab a thermometer and place it in the saucepan as well. Keep an eye on the temperature and the thermostat to check for correct operation. If not within spec, bin it.

Now, if you plan to remove the water pump to inspect it, I'd just bloody well buy a new one. $40 for a new water pump and gasket for a VN-VS V6, cheap as chips.

When you have the thermostat and radiator hoses removed, I recommend to flush and reverse flush the engine block and radiator with clean water. What I mean by this is, hose in thermostat cavity water flows out lower timing cover pipe and vice versa. Same for the radiator, hose in inlet side, water flows out outlet side and vice versa. Continue flushing until clean water flows nicely.

Bleeding the cooling system.
Now, with the coolant level correct and the cooling fan circuit operational, start the engine. Grab a flat blade screwdriver and slowly loosen the bleeder screw on top of the thermostat housing until a stream of coolant appears. Open and close the bleeder screw a few times for a minute or two until the cooling fans start rotating. This means the engine has reached operating temperature. Then just open the bleeder screw and continue until a strong, steady stream of coolant is present. Close off the bleeder screw and you're done! Next thing to do is pack up the tools and work area and take it for a test drive!

Also check the coolant level by the coolant reservoir bottle the next day when you wake up and the engine is cold. Top up if necessary.

I hope this helps you out enough.

 

[VPRob]

good and thorough response above from K-BAGZ. I suggested the booster fan as a culprit because the car runs fine on the open road but runs hot in stop/start conditions where the fan should become operational. The test procedure is there for testing the fan circuit in K-BAGZ's post.
Hope you get it sorted. Let us know how you go

 

[Limpy92]

Thanks K-BAGZ i'm gonna go over the whole car this arvo/tonight and check everything that you suggested. 4 things i realized this morning when i checked my coolant level. My reservoir has a leak underneath it (Explains it being empty alot), my Heater Tap has a leak and my bottom rad hose leaks too i think. When we jacked the car up to do my suspension, there was coolant underneath on the left side of the engine bay (If you were facing your engine, the right side). Now i've only seen it once but i have seen a couple bubbles in my radiator itself, took the cap off, refilled it and as i was waiting for it to drain away. Seen bubbles come up, didn't think much of it at the time. Would someone be able to link me to the page where it tells you how to check fault codes?
Thank you all for your feedback

Edit: There also looks to be a leak at the Thermostat gasket aswell, i occasionally see green fluid surrounding it.

 

[Jonah 101]

You have to do you head gasket if there is coolent pissing directly out of the head

 

[Immortality]

Boiling fluid in the overflow would indicate the radiator cap isn't doing it's job. I've experienced this before, it's bloody weird when you shut the engine down and then you get boiling coolant......

If the coolant system isn't pressurizing as it should than the coolant will boil a lot sooner than it should, thermostat could be contributing to the issue, testing is fine, but seeing as you've already removed it to test it, i'd fit a new one anyway as you never know how long the old one will continue to function properly.

How old is the coolant? does it run coolant or just water? try reverse flushing the radiator, you may have a flow problem.

Bubbles in the radiator could indicate a faulty head gasket. I would do a compression test

 

[Limpy92]

Nothing coming out of the head, just some steam from the back of it. It just gets to the point where it's that hot it boils in my reservoir and dumps basically the whole system onto where ever i'm parked..

 

[Limpy92]

Boiling fluid in the overflow would indicate the radiator cap isn't doing it's job. I've experienced this before, it's bloody weird when you shut the engine down and then you get boiling coolant......

If the coolant system isn't pressurizing as it should than the coolant will boil a lot sooner than it should, thermostat could be contributing to the issue, testing is fine, but seeing as you've already removed it to test it, i'd fit a new one anyway as you never know how long the old one will continue to function properly.

How old is the coolant? does it run coolant or just water? try reverse flushing the radiator, you may have a flow problem.

Bubbles in the radiator could indicate a faulty head gasket. I would do a compression test

Believe it or not i changed the radiator cap about a month ago, might aswell do that again too? I have a feeling my thermostat is contributing the most, as my top radiator hose gets alot hotter than my lower one. Coolant is brand new, ever since it's been leaking out i've just topped up with water (I was always in town when it happened) but when i take the cap off it's still bright green so there's plenty of fluid in there. The bubbling did only start when i changed the radiator cap actually.. Within 1-2 days, could have never thought it could be a problem?