How to diagnose a blown head gasket!! Jeep Wrangler TJ & Terminator cobra testing.

The Mark VIII fan install video referenced can be found here • Lincoln Mark 8 Fan Ins...
In this video I'll take you through the thought process and diagnosis I went through to find a blown head gasket. One of these two has a blown head gasket. Can you guess which one it is before watching? :)
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[@dandookie1738]

Awesome video, absolutely love your content. You have a great way of explaining things and concepts. Keep up the great work!

[@MalcolmV8]

Thanks Dan. I appreciate the feedback and glad you liked the video :)

[@tomriggs699]

Another informative video! Keep them coming!

[@MalcolmV8]

Thanks Tom.

[@mikekosar6135]

My money’s on the TJ..!! LS .. fits..!!

[@MalcolmV8]

lol you've been around TJ's

[@screamineaton]

For the redfire is the boost bypass functioning properly? Ive had mine fail and had and over heating issue from it.

[@screamineaton]

Cams and low vacuum will cause the boost bypass to not operate correctly. Which Im sure you are aware cause of the zinc car.

[@MalcolmV8]

I validated the bypass is functioning. Interesting you had over heating from it. Years ago Whipple shipped out 2.9 blowers with defective crusher inlets that hung the bypass closed and I got one. The blower would get really hot at idle and part throttle driving but engine temps were not affected.

[@dani07april06]

Hey, how would I find the cap for pressurizing the coolant system?

[@MalcolmV8]

The hand pumps made specifically for pressure testing your cooling system will come with a variety of caps made to fit various makes and models.

[@dani07april06]

@@MalcolmV8 thank you!

[@MalcolmV8]

@@dani07april06 no problem. Also if this is not something you'll use much instead of buying one you can do the loaner tool rental from your local auto parts store. You pay for it and they refund you in full when you return it so it'll be a free rental.

[@dani07april06]

@@MalcolmV8 I was wondering if that part was one of the tool rentals. That's great!

[@MalcolmV8]

@@dani07april06 yes it sure is. I tend to buy a lot of the tools since I use them frequently but it's definitely in rental line up.

[@MarzNet256]

Block test for combustion gases. Based on what you are showing, you are pretty much guaranteed a positive result.

[@MalcolmV8]

Yeah the coolant tests are great and work really well.

[@Moe1985]

My Cobra also pushes coolant sometimes out of the reservoir on wot pulls, no overheating at all; I wonder why.

[@MalcolmV8]

Out of the engine coolant or the supercharger coolant?

[@Moe1985]

@@MalcolmV8 Not HE/Intercooler, it’s coming from the radiator reservoir. It’s driving me crazy, no white smoke, overheating, oil in coolant/coolant in oil, coolant loss/leaks etc.. Car has 2.8 KB Mammoth on #17 which is not high boost, I changed the reservoir cap to Motorad just like yours and it still does it. Will try a CFM breather in a couple of days and see!

[@MalcolmV8]

@@Moe1985 if the cap is good and the sealing surface it's mating too then excess pressure is coming from somewhere. Perhaps check for the presence of combustion gasses in the coolant?

[@Moe1985]

@@MalcolmV8 Yeah was thinking about that also. If that’s the case, is it OK to do wot pulls? Thanks, Malcolm!

[@MalcolmV8]

@@Moe1985 that's hard to answer without knowing what's wrong. For me personally if there's an issue I generally avoid WOT till I know what's going on.

[@GaryOaksEgo]

Now my res empties over night without even running and no leaks

[@schubi128]

There is not such a thing like a blown head gasket on a wrangler tj 4.0 😂

[@MalcolmV8]

You’re not joking lol 😂

[@HEYMLO]

Had an 04 with a bad head gasket. I ignored the moisture at the tailpipe, until the top of the radiator exploded

[@MalcolmV8]

@@HEYMLO lol that would do it :)

[@jonc2914]

​@HEYMLO ive had 2 radiator blow up from the top twice in 2 years. My head gaskets fine. It's a weak point on tj radiators.