So I was SUV shopping and found a 2002 4.3 Blazer that supposedly needs head gaskets. I think I got a good deal based on what I paid, what a shop would charge to repair and blue book value. It has only 129k miles so I felt that was good for a 14 year old truck.


I found this article which pretty much goes step by step How to replace head gaskets - Car Forums and Automotive Chat


I should note I am not a real car guy. I am handy, fix printers, electrical work, etc. I have most of the tools including a torque wrench minus some specialty tools like head puller.


I should also say I have not even tried to start the truck. I turned the key on to verify mileage and that's it. The guy told me he got it on trade from folks. They stopped driving it when it got real rough, and I guess its hard to start now, supposedly the plugs are getting fouled up??


My plan was to replace the head gaskets, and already bought a Haynes manual.


But research here shows it may not be a head gasket but an intake gasket which sounds like an easier repair.


My 1st question: Are all 4.3's the same? does it matter which year?


2nd question? what next? run a test to see if it is head or intake gasket? Should I drain all the fluids? I read the coolant is bad for the bearings, will another day or two hurt?


I have an air compressor but what else will I need to test intake versus head gasket?


I appreciate any help

 

Never heard of this.... unbolt and remove head, simple as that.

Yes, the intake gaskets are more prone to failure than the head gaskets on these and is by far a much easier job.

No, they aren't the same. They differ every couple years starting when they 1st produced them..no balance shafts at first, then they added and heads & intake changes, then changed again, and then again....at least 4 x's

You can use a cooling pressure tester, but at this point, it may only leak internally and therefore not SEE where. Also, ppl tell half truths when selling cars -to do that - sell cars. There's no telling how long fluids have been mixing and yes coolant eats the crap out of the bearings. Do oil change in an open pan and see how much mixing is present. Also check in radiator and look for signs of oil. Weighing all of this is how you plan the next move. Post pics of your findings (or videos through Youtube) if unsure on how bad or not bad a situation is.

Compressor is no help in testing but doing a compression test using a tester would. <-- good test to do if all else seems good.

 

As mentioned, faulty head gaskets are not common on this engine. Leaky lower intake manifold gaskets are VERY common.

Get rid of the Haynes manual, it's worthless. Procedures are either wrong or nonexistant. Torque sequences and values are either wrong or nonexistant as well. If you need help changing the oil, the manual is helpful, other than that, forget it. Don't trust it. Improper intake torque and or tightening sequence can cause serious damage to the engine. If you have questions, ask us, we will help you. If you want a reliable shop manual, get a GM S&T series factory shop manual. Usually the cost is ~$200, less if you can find them on Ebay. It is a 3 volume set with over 3,000 pages, and covers ONE model year.

You will need an accurate foot pound torque wrench, and an accurate inch pound torque wrench.

Not all 4.3L engines are the same: there is one "Z" engine, at least three "W" engines, and two "X" engines. Your 2002 has a "W" engine with CSFI and OBDII engine controls. The correct intake gasket set is Felpro #MS98002T.

To test for internal coolant leaks, you will need a very accurate cooling system pressure tester, (or take it apart and look ). A compression test, or pressurizing each cylinder with compressed air, (cylinder leakage) will NOT help in diagnosing leaky intake gaskets. Compression test is for detecting leaky piston rings, cylinder leakage test is for detecting leaky valves.

 

I just wanted to add the red....

 

Yeah didn't sound right to me either just what I read on another article


Ok got it in the garage and set up some shop lights so I can see what I am doing.


Looked on autozone, advanced and pepboys and cant seem to find a radiator tester in stock. How much does one cost to buy?


I found this as a loaner tool. Will it work? Its labeled as an adapter but sure looks like a pressure tester to me. CST/Cooling system tester adapter (9300) | Pressure Tester Adapters | AutoZone.com_


I am going to look and see how to perform this coolant test, in the meantime if anyone has a link telling me how to do it, that would be great.


Can I go ahead and drain all the fluids before I run any test or should I leave them in there till I finish the test? Coolant I can always dump and throw water in for testing cant I?

 

Not really worth buying unless you are a mechanic -ONLY because you need different adapters for testing different vehicles.
It's the tester plus the adapter for testing the cap...lol, yes, name is confusing and this is the tester I would use. Similar to Stant testers -which I love

Eric The Car Guy makes some of the best DIY and How To's on Youtube for general repairs and diagnostics IMO:



You can drain the coolant, not an issue there and you don't need anything in this system for testing. Oil you may want to in case mixing is an issue, if there's coolant or milkshake look, I wouldn't do anymore testing and throw in a used motor (bearings would have been sitting in that "mix" and then repairs aren't worth it) or may not if you plan on cranking it or just refill it with recycled/cheap oil

 

lol I found eric the car guy before I read this.


Ok I am going to get the coolant pressure tester in the morning, from the web I think my local store has it for loan.


guess I'll drain the coolant and oil and snap some pics.


What does the coolant pressure test tell me? If it holds pressure that means the head gasket is good?


Man I am starting to get this sick feeling cause doing an engine swap is not really an option. My wife is going to kill me for buying this truck.

 

If it holds, there are no leaks (internally or external).... if it drops, there IS a leak, then you become a detective to find where...by hissing or seeing bubbles (have windex around to spray at suspected external leaks)
if you watch the video I posted specifically, you should be able understand the cooling concept more completely. The video is also better to comprehend what we're all talking about, watch how it's done and see it performed.

I hate to tell ppl things like engine swap but in the long run it's cheaper to pay 500 or less for engine + parts you may want to replace before putting in, or spending lots of time, energy, patience, frustration and not to mention money for all the parts -for an engine that may not be worth it. Not necessarily saying if/when head gaskets are shot, mostly applies if coolant has mixed into the oil bad enough -then it's not worth it to do the repairs. You can fix all the mixing issues but find an engine knock 1 day, 1 wk, 1 month later after doing all those repairs and spending that money. It's unknown how long before it does knock but it most certainly will.

It becomes a learning experience- NEVER purchase a vehicle without 1st having a real mechanic look at it. Too many things that go wrong in purchases and now more than ever: flooded vehicles, salvage titles, temporary "rigs & fixes" on cars, etc

 

That's the oil color


So I have drained the oil. Next I am going to drain the coolant and video. Then put new oil in and fill radiator with water. pressure test cooling system and use the block tester with liquid.


What if I cant get it started cause of fouled plugs? Will the hydrocarbon test work on crank?

 

No that test wouldn't work until it reaches normal operating temps for starters

That video is listed under private, you need to change the settings that 1 video to public