Have I blown a head gasket?

[Knightmayre]

Hey guys

Is the 3.5 hard to "burp" out air pockets in the cooling system?

I'm afraid I might have done a head gasket though.

No water in the oil and vice-versa.
No white smoke at all.
No loss of power.

However, temp will climb to 100? when I am doing 100, but drop to 90? if I go around 80kph. I'm scared I'm going to warp the alloy heads.

She has fresh oil, fresh coolant (flushed it first).

I've not had a chance to do a compression check.

Any advice?

Thanks
Dave

[bee utey]

100 degrees isn't exceptional for a LRV8 that has an 88 degree thermostat. A wax thermostat goes from cracked open to fully open over about 10 degrees range, it's not a precision instrument. That's why LR put buffered temp gauges in all later products, to stop owners panicking every time the needle moves.

[Knightmayre]

Forgot to mention, it has no thermostat in it right now, I took it out yesterday as it was buggered.
I do have a separate water temp gauge and the sender for that is located in the top hose.

Climbing up the hill towards Kinglake yesterday she hit about 110* then dropped about 20* once she was back on the straight... I've never seen the gauge that high.

[justinc]

No thermostat will sometimes cause overheating as the coolant moves too fast through the radiator. I would be also looking at a partial radiator blockage...

Jc

[Knightmayre]

Thanks JC, but the radiator was flushed along with everything else before I put the fresh coolant in.
I only left the stat out as it was starting to disintegrate.
Also that was with the heater on high, belting out hot air - I was roasting lol

Cheers
Dave

[PhilipA]

No water in the oil and vice-versa.
No white smoke at all.
No loss of power.it is pretty common in the old 3.5s to have the outside bolt on the heads pull the outside down and lift the inside of the head, causing a leak into the valley.
No water in oil as the waterways are at each end only.
No great loss of power but if you compare to a fresh engine it will be down
no white smoke.
under extreme circumstances it can pop the valley gasket but usually they will go for years with the only problem being gradual heating as you go faster.
They will eventually burn a channel from the cylinder to the valley so may be good to change.
Do a compression test first.
Regards Philip A

[loanrangie]

Flushed doesn't mean it isn't blocked , how old is it and do you know it's history ?

[Mercguy]

Flushed doesn't mean it isn't blocked , hold old is it and do you know it's history ?

Totally agree. Speaking from experience. even if it is acid cleaned and flushed, it could still be 80% blocked...

[DoubleChevron]

Yeah, as the guys state, you need to take the radiator in and get it "rodded" out. Basically they will unsolder both the tanks and push a rod through all cooling tubes to clear it.

I've tried it myself an never been successful. The tubes were so blocked I could get anything to pass through them :o.... Then you have the "fun" of soldering it back together if you do succeed.

seeya,
Shane L.

[DeanoH]

With no thermostat there is nothing to regulate coolant flow or temperature. Replace the thermostat first and see if temperatures stabilise.

I can't remember if the 3.5 V8 has a bypass thermostat or not. If so it is very risky running without a thermostat as coolant flow is so compromised that head failure is a real risk.

Yes, the Classic can be a bit of a bugger to bleed the air from, that's why there's a big brass bleed screw up high on the heater coolant pipe on the LHS of the engine. I used to take the heater hose off at the bulkhead and use a short length of heater hose to raise the bulkhead heater pipe connection when bleeding.

Deano :)

[superquag]

Compression test results ?:angel:

[PhilipA]

Is the 3.5 hard to "burp" out air pockets in the cooling system?
I just remembered this one.
Is this engine an old carby Job?
If it is another cause of overheating is blocking with rust of the little pipe from between the carbys to the radiator which causes an airlock in the manifold.
The fix is to just get a drill and run it through the little pipe until coolant comes out.
Regards Philip A

[Bundy]

Have you actually pulled the radiator out to clean it or done it in the vehicle?
Mine used to get heaps of leaves and stuff between the AC condenser and the radiator blocking air flow.
Is this the car with all the spot lights on the bull bar? Take some of those off and see how you go. Has the viscous coupling on the fan still got drag? The idea is as the rad heats up the fan speed increases and roars more.

If all that is OK I would get the rad rodded as the other guys suggested.

Good luck Paul