Question for all you guys with experience using the auto zone block tester (2 Viewers)

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Joined
Nov 26, 2012
Threads
10
Messages
56
Location
Salem, OR
Short back story, I the phh on a road trip a few weeks back, caught it early and managed to limp it home. A week ago climbing the pass I noticed the reservoir was filling, followed by air bubbles, dumped it back into the radiator and didn't have any more problems the rest of the trip. This week it started to do the same thing so I decided to try out the auto zone block test.

One thing I noticed is everyone seems to do it right off the radiator, but the people demonstrating the tool on YouTube seem to always use the overflow tank. Is there a difference?

I tried both ways, off the overflow (connected a small tube that fits in the vent and the tester) and off the radiator. I sucked down the coolant to just above the fins, but if I pump too hard it shows color change, but I also noticed coolant pooling in the radiator cap spot which makes me think false positive.

If I pull directly off the overflow bottle, I get zero color change. Even while the dip tube is bubbling.

As far as headgasket symptoms, it shows no others out side of the bubbling, and maybe a little coolant loss.

Any one have an idea how to interpret the different outcomes?
 
I don't really understand what you are asking? It won't work if you suck up any coolant. If you read the directions it shows exactly how to use it. As long as you are sucking air and not coolant it should show if there is combustion fumes in your coolant. I always use it off the top of the radiator.
 
That answers my question, the kit I got did not come with instructions. I was wondering the validity of testing it off of the reservoir.

As far as overheating it does not, though they are higher than normal. The only symptoms I'm chasing is the bubbling and filling up the reservoir. Like to the point of over flowing this last weekend.

Just wondering if I was using the block tester properly. Thanks for the replies. I ended up ordering the dual chamber tester, so tomorrow I will run it again.

Thanks guys
 
I did it on my daughter's honda off the radiator, not the overflow tank (NAPA tester comes with instructions and that's what they say to do). There was only a slight color change in the fluid (went from blue to blue/green, not yellow as the instructions say will happen with a blown gasket), but the gasket was indeed blown--driveable but would overheat on longer trips with AC, almost un-noticeable in winter time. If your HG is good, the fluid should not change color at all.
 
I use the NAPA version also, it can be used off of either the radiator or coolant overflow. If you use it directly in the radiator you will need to have the cap off, engine idling and warm and an air gap below the filler neck so as not to ingest coolant when pulling air with the bulb. As far as color change goes, if you have a blown head gasket the fluid will turn nearly clear if it's bad enough, like light colored piss, have witnessed it myself a number of times, if you're having a very slight color change as mentioned above, no real worries there.
 
Pull some exhaust into the tester. This will make the magic fluid change color and you will really know what your looking for.
 
I never watched any Youtube video, I just use it directly over the radiator cap - if you have hydrocarbons leaking into the coolant, it'll turn from yellow to blue fairly quick & real obvious.

I did it this way forever ago on VW's as well - they were pre-expansion tank era watercooled.

Only useful info you get out of the expansion tank is if yours is clean enough fluid & you see grey/tan sludge in the bottom of the tank - that's exhaust/hydrocarbon solids.
 
If any coolant gets in the tester it will provide a false positive...ask me how I know. So be sure to drain it down low enough. As far as the air bubbles go have you tried parking the truck with the front end up hill? Let it idle with the cap off with the radiator being the highest point in the cooling system to help purge any trapped air in the system. And be sure both heaters are wide open to get the air out of them. Worth a try.
 
I could smell the exhaust gas in my overflow. I kept telling myself I was fine and I drove the thing for a year that way. Just kept replacing coolant. I sold it to a guy (he knew!) and it eventually blew all the way about 6 months later. Mine never registered on one of the testers like you are using.

Sounds to me like your Head gasket is probably on its way out.
 
Sounds to me like your Head gasket is probably on its way out.

I'm thinking you are correct

So I got a hold of a dual chamber tester, basically two bubble testers stacked, but the first chamber is supposed to grab any alkaline to keep from having false positives. First the lower chamber turned yellow, than the upper. Sucks cause the rig has been running so well lately

20160607_175615.jpg


Guess it's time to start collecting parts so I can join the hg club.
 
I'm thinking you are correct

So I got a hold of a dual chamber tester, basically two bubble testers stacked, but the first chamber is supposed to grab any alkaline to keep from having false positives. First the lower chamber turned yellow, than the upper. Sucks cause the rig has been running so well lately

View attachment 1271540

Guess it's time to start collecting parts so I can join the hg club.
Oh crap, you're only an hour north of me.
 
I did my head gasket as PM. Make sure you have all the seals you need before going at it. I replaced my timing chain, resealed my oil pan, replaced my radiator and hoses and replaced my coolant hoses and heater control valve while I was at it. Just a lot less to worry about in the long run.
 

Users who are viewing this thread

Back
Top Bottom