What may be causing the bubbles in the rad ??

[Mr DJ]

Well after finding bubbles in the rad & pressurising the rad at operating temp to find condensation initially coming from the exhaust, I pulled the heads of and sent them to be crack tested & faced.


Wynnum Engine Reconditioners tested them and found no cracks but needed 8 thou to face them (previous gasket marks could still just be seen in a couple places) and a valve grind while out to ensure excelent valve sealing seemed smart while they were out.
Had to buy a set of ARP head bolts ($60) as they were not used as promised in the initial rebuild


Fel-Pro VRS gasket set was used (nice kit) and at 2:30am Friday morning it was almost back together.


Had to get a few little things when the sun came up, idler pulley bearing was bit sad & broke a couple of injector locking clips in my rush to pull the heads off on monday night to get them to the machinist.
All back together and started straight away :peaceout: I thought all is great, so changed the oil & filter, bleed the cooling system, loaded the rig & trailer and set off for The Hilux Meet around 4:30pm.

Just after getting on the highway (not far from home) the temp climbed to 100deg so cruised back home to sort the problem which I thought to be a thermostat as it was holding 100deg all the way back.
Pulled the thermostat, tested it in water on the stove and was open before it reached a simmer so that was not the problem.
All back together again, bleed it for 2hrs + a short run up the street and STILL getting some very fine air bubbles out the rad.

Thinking it's an air lock somewhere but otherwise I just about out of ideas.
Short vid below.

[BumbleBee]

Is the radiator cap the highest part of your cooling system? Did you remember to turn the heater on whilst bleeding the system? Have you tried the old coke bottle trick in to raise the height of the coolant whilst your bleeding the system?

[Mr DJ]

The coke bottle trick I have not tried but will tomorrow, thanks.
Squeezing the heater hoses does make the coolant rise but no extra air bubbles.
Yes, heater tap open.

[BumbleBee]

I have to use the coke bottle every time on my hilux as the turbo coolant lines sit higher than the radiator cap, its the only way to get all the air out. Dont fill the bottle too high initially as the coolant will rise when it gets hot.

I'm thinking about emailling coke to get them to re-enforce their coke bottles, i have had them colapse from too much heat. haha

[Mr DJ]

No change after trying the coke bottle trick ....

I know there are some really switched on guys here, so throw your ideas out there cause it may just put me on the track to the solution.

[rockcrawler31]

Is there flow across the rad when the thermostat is open? have you pulled the pump to check that the vanes are still good? If the vanes are rooted or if the pump is overdriven too much it's possible the bubbles could be coming from cavitation.

[turbo gu]

I am guessing ford EFI motor?
Does it have any coolant lines thru the manifold? They could cause a air lock if they are higher than the radiator cap. A bit odd that after that much driving it hasnt cleared yet.
Have you had your radiator checked? Possibly partially blocked core maybe?
Check the temp across the radiator fins.

[Mr DJ]

rockcrawler31 - There is flow across the rad, I have since found an old thermostat I may cut the centre out of it and put that in while problem solving to eliminate it.
No, I have not checked the pump vanes but had a new pump installed during full rebuild less then 5000km ago so should be fine. Std pulleys used will not be over driven.

turbo gu - Yep, Ford Windsor EFI.
Yes, 1 small feed & return line to upper manifold via factory engine heater pipes. They are higher than the rad but the heater tap is higher than that so would be forced through.
Good idea on partially blocked core. How do you properly clean the cores on an alloy rad as the tanks are welded on ?
Will have to pull the fan and shroud off, re-bleed system and check for hot/cold spots.

[turbo gu]

Those small lines shouldnt cause any problems.
The only way would be cut the tank off.

[want33s]

302 plus how much overbore?
Could be a pinholed bore casting.
Could be head gaskets on backwards.

[Mr DJ]

Bore is only 20 thou over.
Impossible to put the Fel-Pro kit on backwards as the inlet manifold gaskets interlock into the edge of the head gasket protrusion + they have the "TOP" stamped into them.

[RED60]

Did the same mob that put the supposed ARP bolts in do the new waterpump and the impossible to put on upside down/back to front head gasket as well..........

[Mr DJ]

No, I definately did not re-visit Adrian Liefels from Jimboomba (he hung up in my ear when I tried to "discuss" the matter)
Because I pulled it down is the only reason I know old/corroded head bolts were used and not new/ARP ones.
I put the new waterpump on. Did the heads also with some experienced & qualified help (thanks Scotty) just to be 100% sure it was done right.

[Mr DJ]

And the winner is .... turbo gu
Thanks to everyone who helped with ideas or suggestions

Turns out the rad was almost completely blocked
The little bubbles were from coolant in the blocked tubes boiling.
Was pressure cleaned with 200psi to get most of the crap out, but he still guesses at 20-30% blocked without cutting off an end tank. Apparently it will then be difficult to re weld as the ali absorbs some of the glycol in the coolant. Will pull it again and try to dislodge what's left.
Good news is I could not get the temp above 90-92 deg and I was giving it a hard time !!

The bottom feeding, low life, ripoff, piece of ..... that built the engine obviously never cleaned out the block or properly so all the crap that was left in it was just pumped into my new pristine rad.
I did flush the block prior but that was obviously not enough for all the scale/crud that was there.

[turbo gu]

Glad it was a relatively simple repair for you. I have had a few customers cars over the years that have had similiar issues that turned out to be blocked radiators

[Clanky]

I too have had great radiators ruined by this same problem.
Now I run one of these filters for a few months after the build, then when no more crap comes out I just take the filter mesh out.

http://www.ebay.com.au/itm/TEFBA-WATER- ... 1e5c03515f" onclick="window.open(this.href);return false;

Frank (TEFBA) is a good source for custom wheel studs and stuff for race cars etc. Located out near Oran Park NSW.

[Mr DJ]

Thanks Clanky, I actually rang & ordered one from Frank this morning ($72 delivered) and will be here on Tuesday
Very nice bloke with a wealth of motoring experience he is eager to share.