1994 Rav4 Blown the radiator

[Derek L]

Hi, Hope one of you guys can help explain this one ? Bought a 94 Rav about a month ago , noticed that i was losing coolant then noticed leaking from radiator , mechanic said it was history so got a new one fitted also rocker cover gasket as that was also leaking. All was sweet then noticed lose of coolant again , back to mechanic who thought faulty radiator BUT looks like radiator blew cause to much pressure saying that head gasket failed and cylinder is sending excess pressure through the coolant channel and thats the problem, well rather than spending massive bucks with mechanic we stripped the engine down ourselfs to find perfect head gasket NOT blown , compressing rings not cracked. Is there another way that the coolant is getting undue pressure on it to cause the radiator to " as my mechanic said balloon out " ? Also there is 2 styles of head gasket for this model they are slightly different 1 has a few more coolant holes than the original why ? Thanks for any advice Cheers

 

[campbeam]

Interesting tale so before responding, did a Google search for the following URL

http://auto.howstuffworks.com/cooling-system7.htm

This explains why I found it hard to accept. I would expect any excess pressure to have vented through the overflow bottle. Even with a faulty radiator cap, there are plenty of connections and hoses in the cooling system which could have failed before the radiator. A compression check of the cylinders should have been able to detect any loss of pressure into the coolant system. Also with the radiator cap off, you would be able to see bubbling in the coolant.

[Derek L]

Thanks Ashley, Yes i agree makes no sense, but because of the advice of the mechanic , a weekend of stripping down to the head gasket to find that its not been breached has really ****** us off, 

 

[Derek L]

so would you say a faulty cap could have cracked the new radiator ?  

[trentmeyer23]

Coolant pressure test and cylinder leak down test would have prevented this work. They are still valid tests if you have it back together.

[Derek L]

Hi havent put her back together yet, as still trying to find out if there could be another reason why the mechanic would point me in the direction that it was the gasket ? There was no bubbles coming up from radiator prior to strip down, and why would the cap not relieve any pressure in the coolant as its going in radiator ? Rather than swell and crack

[trentmeyer23]

The cap can also be pressure tested.

[Derek L]

Well the story so far , took the head and gasket to engine machinist , head was warped and gasket had failed between 2nd and 3rd cylinder and across to 2 coolant channels beside return oil channel which had excess presure thr coolant that has cracked radiator .After picking up resurfaced head the mechanic said i have 2 gaskets to choose from ? Original BR250 or BS970 the 970 has 4 extra coolant holes , now im totally confused. Would the 970 allow a higher flow of coolant that would keep the engine cooler ? Or should i just put the new original back ? One more question has anyone cleaned the mud out of the block while still in engine bay, and if so how did it go. Cheers