Split 2 radiator hoses in one week.

[Z1XX3R]

Today would have been the second upper radiator hose that I have split in one week. Both of these hoses weren't brand new but they were in decent condition. I popped my radiator cap to find oil in there but when I went to check my dip stick it was perfectly fine with no coolant mixed into it.

Now before everyone starts to say that I have a possible BHG let me give you a back story about my car....

I recently bought it from a guy that had just swapped the motor out to put a low mileage motor into it. The original motor that he took out had a BHG and the mechanic did not swap out the radiator which had all the nasty coolant/radiator in it. So the radiator and the whole cooling system already has this nasty mixture in it. I've done my best to flush out the system but still have some residual in it.

Now going back to my oil in the motor...it doesn't show any signs of coolant in it but the radiator clearly has oil in it. Is it possible for the oil to go into the cooling system and NOT back and forth? Any ideas or any advice is greatly appreciated. Thanks.

Kleigh.

[Skym]

Thermostat sticking closed and overpressurising cooling system can blow headgasket, radiator hoses, waterplugs on side of engine, etc. Dropping coolant level in radiator is another symptom of this happening.

Usually a leak goes from high to low pressure zone. But black in cooling system could mean a leak from cylinder to cooling system (I think it usually goes brown) or radiator might need to be removed, top tank removed, rodded, new gasket fitted.

Pressurise cooling system via where radiator cap goes (radiator pressure test kit) and see if pressure drops. If it doesn't and there's no external leaks, then headgasket, etc should be ok -

http://www.youtube.com/watch?v=96aQ5DD5y78

[caliber676]

The water pump is a displacement pump and therefore does not create pressure persay (maybe a couple psi) it is simply there to flow the coolant through the engine. The temperature rising, fluid expansion and the radiator cap holding that pressure in until the set relief pressure is reached is what causes pressure rise.

Blockages and such will only hinder coolant flow and cause overheating as in the case of the thermostat. Overheating can cause head gasket failure but not from pressure build.

My money would be on your rad cap.

[Skym]

The temperature rising, fluid expansion and the radiator cap holding that pressure in until the set relief pressure is reached is what causes pressure rise.

When thermostat sticks closed it doesn't allow coolant to dump into radiator and be cooled and the coolant heats up and expands (like it does into overflow bottle).

Blockages and such will only hinder coolant flow and cause overheating as in the case of the thermostat.

I agree.

Overheating can cause head gasket failure but not from pressure build.

The aluminium head warps and crushes headgasket causing seal around cylinder to fail. Metal headgasket has some resistance to this.

Stock headgasket doesn't seem to be that strong, seen some where it blows around coolant gallery. If it was a metal headgasket I would agree. I have only seen a metal headgasket blow seal around the cylinder (I assume due to head warping, but never was told the cause), engine run rough.

My money would be on your rad cap.

I think you might be onto the problem, blocked radiator or radiator cap problem might be a cause since they weren't replaced. Doesn't hurt to change thermostat at same time which might have been affected by the extra heat.

[Z1XX3R]

So no one is suspecting a bhg yet? Is it possible to just have oil go into the cooling system and not vise versa? Now that I sit back and think about it, I have noticed that I hear a lot of my clutch fan. There is something definitely wrong with my cooling system.

Is there any way for me to COMPLETELY flush out all of the oil out of the cooling system? Thanks again guys for all the help.

[Skym]

Do the pressure test on radiator, coolant visual check (not brown, should be bright green), oil dipstick tip isn't milky looking. If those area's are ok I would look elsewhere.

If hear noise around waterpump, the waterpump could be one the way out (same thing happened to my cars waterpump, as started to make noises) and it can cause overheating on motorway if the blades have worn away (struggling to move coolant into radiator to be cooled) and that happened to someone on here. Waterpump would start leaking if it fully failed. I was told the centre part collapses and leaks through a small hole on the front.

I think more the radiator core could be blocked, full of oil, etc and like said above the radiator cap could be part of the cause. I had 30% 1st time and 15% second time of crap built up in radiator when tested before cleaning (removed top tank, rodded core, fit new gasket for top tank, etc and then removed bottom tank second time after a few years). That's why the top, bottom tanks on stock radiator are removeable. With racecars you woud replace radiator.

Oil could have got into aircon heater core, radiator, etc and they probably weren't cleaned out properly.

[Z1XX3R]

So I've flushed out my cooling system and I still have the same result, I have a lot less oil but there is still oil in there. I've found a stock radiator that is in good condition so I'm going to swap that out in hopes that it rids the most of my oil issues. Do any of you think that I might have messed up any of my temp reading sensors as a result of all that oil?

[playtime]

If you have coolant in oil or vise versa it is an indication of a blown head gasket. If the gasket is blown it causes increased pressure into coolant causing more than one hose in a row to blow it is a good indicator. The head gaskets job its to keep oil out of coolant and from collant from contaminating motor oil. Do a pressure test on the coolant and see if it drops pressure or increase pressure than normal. I am sure this is your issue
Ian