Bought our 02 4.3 4x4 Blazer in 06 with a little over 48000 miles on it. Never had a problem with our blazer. Now with 140,000+ miles. This time last year the radiator cracked while my wife was driving to work, and she shut it down quickly. Had it towed to the house, checked and made sure no coolant was coming from any other place, then started it, it ran fine, no internal damage. Upon further investigation, the inside of the hoses and radiator where baked and caked with dexcool. (After cool down)Flushed it with water, then ran it and flushed it with radiator flush with the old radiator on it, it cleaned quite a bit out even though it leaked, as I was hoping it would also clean out the passage ways in the engine it self.


Before replacing the radiator, I waited to be able to replace the cracked radiator, plus all the hoses and water pump. That was Sept. It ran great until I noticed a small leak between the intake and the heads, just a trickle. second week, I started it up and a light tapping sound started, then stopped after warm up, no service lights on. I drove it for a couple more days, and then the service engine soon came on, I then parked it until I can fix it. I found that a coolant leak from the intake into the lifter valley caused this tapping, and sense there was a coolant leak present on top of the intake, this all made sense.


Got everything I need to perform top end gasket/rebuild, I will be replacing the head gaskets also. along with new cap, rotor, plugs, and wires.
got a lot of info from this site
Index of Engine Repair Articles - HandyManlyNess.com. more along with the Haynes book it helped tremendously.


Q. He mentions on that site using a 7/16 coarse tap to chase the threads, I thought this engine was all metric?


Any other input will be appreciated also.


Have been starting it every week to keep lubed, this last time ( and will be the last time as I start tomorrow on it.) I unplugged the coil wire, cranked it a couple of times then started it up, a lot less noise this final start, and stopped a lot sooner upon warm up.. Just confirms the results of coolant leaking in to valley and causing the tapping, coolant getting in to intake port causing service light. Research on this has taught me the Original intake gaskets over time on the 4.3 break down, and is quite common.


P.S. the radiator cracked from over heating, not just because its plastic there, but because the reserve tank became clogged, (from dexcool, who knows, mainly my fault for not checking it regular) and starved the cooling system from coolant.

 

You will most likely be losing some engine bearings since the coolant was in the motor oil for such a long time. It does not take any time at all for anti freeze to destroy engine bearings so be a whare of what may be coming.

 

Doubtful, Bearings only go out when not lubricated under pressure properly. Not enough coolant in the oil to effect that. Plus I put Seafoam in it the the day it started ticking.

 

Only bad thing about this job is the freaking wire harness being right in the way of everything. Will be zip tying it up out of the way tomorrow! Engineers, pff!

 

If there was enough coolant in the oil to cause lifter noise, there was enough to damage the bearings. Hopefully you caught it in time. Coolant is heavier than oil. When the engine is off, the water separates from the oil and settles on the bottom of the oil pan, right where the oil pump pick up is. When you start the engine, the pump sucks the coolant first, and sends it right through the crankshaft to all of the main, rod, & cam bearings. The lifters are the last thing to get oil. Cross your fingers


Don't put too much faith in the handy manly website info, especially for lower intake manifold gasket replacement. Several important things were left out, and some of the information is flat out wrong. Same goes for Chilton/Haynes, worthless. If you want accurate information, invest in the GM dealer issue shop manual. eBay usually has used ones at reasonable prices. Each manual is year specific, so make sure you get the correct manual.


The heads and block are SAE, not metric. The intake manifold bolts, head bolts, rod & main bearing cap bolts, exhaust manifold bolts are all SAE. Rule of thumb is if it bolts to the block, it's SAE. Everything that bolts to the intake manifold itself, is metric.

 

Haha chuck, I was thinking the same thing......if there's enough to cause lifter noise...........

 

Yeah I know, he did a lot of things wrong (handymanly) and I agree about Haynes, not enough specific info, they left a lot out. Decided against replacing the heads, compression is good, no visible leaks, and the original spark plugs all looked good. The intake gasket looked like every picture I have seen of them, failed at the same spot. Pitting was not bad on head and intake, and cleaned up smooth. Used felpro intake kit MS98002T. I also put new O-ring set in the injectors, fuel meter, and lines.




"The lifter makes noise at first start up because, the coolant leaks down into the lifter when engine is off and washes the oil out of it, so it has no prime at start up, and continued use of vehicle will eventually ruin the seals in the lifters." So it`s not the coolant in the oil, it`s the coolant leaking into the lifter while the engine is off.
As I said before in my first post, I started my blazer every week just up to temp with no coolant in the oil or cooling system with no noise at all. When I finally got the new radiator, pump, and hoses, it ran for 2 weeks with out a hitch, and then the lifter tapping started, I drove it a maximum of 20 miles in 2 days when it started. I have already talked to a master mechanic (my nephew) who reassured me of everything I just stated. And affirmed that there was hardly a trace of coolant in the oil to affect the main bearings in that period of time. And all it takes is just a couple of drops of coolant in the lifter to wash out the oil when engine is off. I would post some before and after pics, but I don`t know how to on this forum.

 

Thanks for the info on the threads, SAE vs Metric, Captain!

 

"The lifter makes noise at first start up because, the coolant leaks down into the lifter when engine is off and washes the oil out of it, so it has no prime at start up, and continued use of vehicle will eventually ruin the seals in the lifters."


Interesting theory, but unfortunately it "doesn't hold water", don't trust it. #1 There are no seals in a valve lifter. #2 The intake gaskets can only leak coolant internally at the 4 corners, which means it could affect 4 lifters, at the most. The problem is that the lifters aren't even close to being inline with the coolant passages to drip coolant into them. Even if the coolant could drip onto a lifter, it wouldn't displace the oil already in the lifter.

 

This is what I meant; The metering valves, check ball, and the piston/plunger are the seals I`m talking about. And when the engine is shut down and is spraying coolant in the valley it`s going to make your lifters do some tapping. I did test while I had the intake off to see if a slow leak could dribble onto a lifter, some times yes, and sometimes no. all depends on where the leak is coming from that coolant port.


FYI- while I had the intake off, and cleaned as much gunk out of the valley as I could by hand and shop vac. I also squirted a quart Rislone engine treatment everywhere in the valley to help clean the rest of the gunk. After everything was back together, and started to change the filter and oil before starting it up, the filter had gunk in it, and I got the scare of my life when I pulled the drain plug and no oil came out. Then it pooped out some gunk then oil then gunk etc.... I am glad I dumped the Rislone in there, as it sat for 2 days. After it all drained out, I put another quart of Rislone in, and let it sit for a couple hours, the drained it, and filled it with a quart of Rislone, and 3.5 quarts of oil, Moral of the story, drain your oil if your vehicle is going to set for a while.


Coolant in and ready to fire it up, cranked it with the coil off to prime everything, heard a weird tapping sound, surely it`s not the lifters. Anyway coil wire hooked up, she fired right up!
Still heard a tapping sound, not the lifters, coming from the distributor, bearings are old and causing the 3 (new rotor)rotors ridges to hit the contacts in the new cap. Now I need a new distributor, Temp fix, file the ridges down a little where you see the marks from it hitting. reinstalled, success, no noise!
Took her for a test drive last night, and ran like it was brand new, no leaks, smooth, and more power! Did not get enough pressure in the cooling system to rule no leaks in it yet. Hope all goes well today in a longer test drive.


Thanks for the feed back everybody.


P.S. Before fixing the tapping coming from the rotor, it did not effect the engine, no missing, etc.. I`m sure if I did not correct it right away, damage would result. Plan on buying a new distributor ASAP. Any suggestions? Aluminum?