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Author Topic: Does this gunk mean I have an internal engine coolant leak?  (Read 2774 times)
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Tronman
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« on: February 01, 2018, 05:58:26 PM »

So while I was working on the EGR valve, I happened to check the oil.  It looks a little dirty, but still translucent and honey colored on the stick like always.  But when I pulled the PCV valve, there was this yellow gunk under it.  I stuck a finger into the oil cap hole and this came out.

I've seen it have some condensation under the oil cap in the winter, but never thick gunk like this.  There are no visible external coolant leaks such as the LIM, for which these engines are known.  But before the weeping and head gasket R and R out in the rain begins, I thought I'd run this by the ole' Aztek hive mind.

This engine has been well maintained and it has never overheated, and I've never had to take any of its lids off-however it does have 227K miles on it.
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wstefan20
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« Reply #1 on: February 04, 2018, 07:02:40 PM »

Well that is strange.... usually coolant mixed with oil is milky and chocolate colored. This definitely isn't normal. Have you been losing coolant recently? If so, I'd rent a pressure tester at oriley's before condemning the engine. Any other info that might be pertinent?
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Tronman
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« Reply #2 on: February 10, 2018, 12:20:13 AM »

Can't think of anything.  The vehicle has used slightly more coolant lately, but it's had a slow radiator leak for some time.  Due to a lean running condition which I believe to be the cause of a random misfire which causes the engine to go into OLD (basically return to a sputtering idle) like clockwork at 41 percent calculated load..  I'm taking the top off the engine for LIM gaskets anyway.

Since LIM is about eighty percent of the way to head gaskets, I'm gonna do 'em while I'm there.  Still hyped on my Aztek overall, I intend to keep it for another 200k miles..  plus the bottom end is solid, it's never used a quart of oil in total for the whole time I've owned it.
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Tronman
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« Reply #3 on: February 11, 2018, 01:26:44 AM »

Yep, there's an internal coolant leak..

But I'm not entirely sure it's the head gaskets..  As you can see in the pic, I caught it pretty quick as the gunk hadn't even spread all the way from the rear of the engine to the front..  (left side of the car to the right..)
« Last Edit: February 11, 2018, 01:28:02 AM by Tronman » Logged
Tronman
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« Reply #4 on: February 11, 2018, 01:31:58 AM »

The other thing I noticed is that when I removed the LIM, the rearmost bolt to the right was barely tight at all, like almost finger loose.  The others were all regular torque and required some effort to loosen.  Are the LIM bolts torque to yield?  Do I need to replace them?

This is all removing factory parts, no one has ever taken this engine apart before.
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Tronman
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« Reply #5 on: February 12, 2018, 04:59:12 PM »

Well I got the heads off..  it wasn't the gaskets.  They looked great.  No evidence of leakage, it was all the LIM :-/

So I went a lot farther than I had to..  but I'll still take the heads in and have them cleaned, checked, and the new seals installed.  I suspect they're fine.

On the plus side, I found some broken exhaust manifold studs and some leakage, and boy will those bolts be easy to extract now versus on the engine..  Also fixing those leaks will reduce the incidence of air (oxygen) being sucked into the exhaust stream, fooling the computer into thinking the engine is leaner than it is.

Also on the plus side, the cylinders look fantastic!  You can still see some factory hone marks, there is no ring groove at all in any hole!  No wonder it's never used any oil.  So I feel pretty good about putting a freshened set of heads on this seasoned bottom end.  Also, I found the cold engine clickety clatter..  when I turn the crank back and forth, you can hear the timing chain go click click.  However it's only two degrees or so of engine rotation, still tight.  Wondering if I should bother replacing it now while it's all torn down..?  It has made the exact same noise when cold since the day I brought it home, BTW.
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wstefan20
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« Reply #6 on: February 13, 2018, 08:25:53 PM »

Nice work! I don't think the lower intake bolts are tty, but I always use thread sealant on them (service manual says to at least for the 3100 engines).

Personally, I'd replace the timing set since they are relatively cheap, and you'll never have a better time to do it!

Be REALLY careful on the torque sequence and tightening when you replace the heads. I personally recommend having the machine shop resurface both the block and head, but in a pinch, use acetone and a plastic razor blade to get the surfaces clean. Don't use a metal scraper (ask me how I know).
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Tronman
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« Reply #7 on: February 18, 2018, 09:50:22 PM »

Good call on the thread sealant!  Back in the day, we used to use the white liquid teflon stuff on SB Chevy V8s for the bolts that went into coolant passages.  Will that be adequate?

The heads are in the machine shop now, I'll talk to Wes (NAPA North Bend, WA machinist w/30+ years experience) tomorrow and see how it's going.  I'm considering having a little port work done if it's not terribly expensive..  hey, while the heads are in hand, right?  I'll take 8hp if I can get it.

Will straight edge the block after careful cleaning.  But the engine never got hot, so I'm kinda doubtful that anything warped.  Also good advice about the plastic scraper, as I would have just cleaned it like every other cast iron deck I ever cleaned-and smoothed out with a fine flat file.

Slightly on a tangent..  I'm perusing the Fiero and F body forums and seeing people put rather a lot of work into the old '80s 2.8 version of this engine.  They're doing aftermarket cams that are good to 5000 RPM, and putting all this money into flogging those ole' small journal horses.  Seeing as how the far superior, lighter, 3400 version has modern day alloy heads with 50cfm better flow, (oops, it doesn't have roller rockers, I meant to change this before this went up) and will do 6200 RPM no sweat..   and can be had for a dollar fifty a pound at any wrecking yard in the country because GM made a gazillion of 'em and no one hops up minivans..  why would anyone not simply go this route instead?
« Last Edit: February 28, 2018, 07:11:51 PM by Tronman » Logged
Tronman
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« Reply #8 on: February 28, 2018, 07:15:49 PM »

The machinist said my heads looked great-very minimal warpage although he did mill them a little.  Had the stem seals installed too, he said the valves and sealing surfaces looked great, also passed a vacuum test with flying colors.
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Tronman
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« Reply #9 on: March 21, 2018, 09:16:49 PM »

I got my heads back from the machine shop today.  Also worked on cleaning the block decks.  They're even cleaner than in these pics, but I think they're getting there.

My question tho, is which way the head gaskets go in.  All the holes seem universal, like the gasket could go in either side up and everything lines up the same-but the steel rings are discreet on one side of  the gasket, and connected on the other.  See pic..  which way should go up towards the aluminum head surface?  Does it matter?
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« Reply #10 on: March 27, 2018, 05:46:55 PM »

Your project seems to be going very well and it sounds like your engine is in really good shape. I don't know that I would be looking to increase the power unless you are doing rings, rods and bearings. Those hard parts may have weakened from heat in an engine with that many miles on it.  

As far as your question about the orientation of the head gaskets, if it is critical, it will be marked. if it isn't marked, it doesn't matter which side you put up. What brand of gaskets are you using?
« Last Edit: March 27, 2018, 05:48:36 PM by Tom Moog » Logged

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Tronman
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Any car gets great mileage when you ride your bike


« Reply #11 on: April 02, 2018, 08:40:49 PM »

Well I've got the right head on, though not torqued.  The bolt kit came with the correct number of bolts, plus an option for the big stud sticking out the front left head bolt where the dogbone mount goes.  The kit also comes with another short length head bolt having a smaller threaded stud sticking out the top of it.  I can't remember if I took one like this out or not and I foolishly recycled the old bolts already.  Does the right bank lower front head bolt on the Aztek have the smaller stud sticking out of it?

Other than that conundrum, it's going well, if seemingly infinite in its fiddly little details that have to be right to do a good job.
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Tronman
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« Reply #12 on: April 03, 2018, 11:42:48 PM »

Today was frustrating.  Got the rear head torqued down, which went fine.  Then the radiator installed, which didn't..

Never buy the cheap radiator from Amazon.  See that gold colored metal clip?  It was in the wrong place, and I had to drill new holes to hold it in the right place.  Also those little black rubber nubs that go between radiator and A/C condenser?  No holes for those in the new radiator either, so I made some in the same place as the factory radiator.  Which, it turns out, wasn't really bad either, it was just leaking subtly from a hose port.  Well, it won't leak now.

Especially since the lower hose came from Amazon, even tho it was a Gates part, too short!  It seriously looks like someone cut the end of it off and then returned it, so I'll just buy the right one from NAPA in the morning.  More hassle..  so after installing this radiator the first time and not being able for the life of me to get the fan module to sit correctly (see misplaced metal tabs above) I installed it the second time and it went in.  Only just..  I think how they want you to do it is evacuate the A/C and crack open the condenser fittings, then put the whole shebang together on the bench and then install the assembly.  I didn't do that, so it took for freakin' ever to get all those little tabs and bolts holes to line up.  And then, just to spite me..  the little nipple where the overflow line goes into the radiator WAS TOO SMALL!! I almost started throwing things.. However, the little rubber cap they seal it with for shipping, was just the right OD to match my tube.  So I snipped the closed end of it off, put it back on the nipple and then slid the hose over it, then the clamp held it securely.

So I don't have any extra parts and everything is straight and tight :-)  Tomorrow: the other head, the valve gear and maybe if I have time the dreaded LIM..

I still have a mountain of wires, tubes, and mounting brackets to remember where they go..
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Tronman
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« Reply #13 on: April 03, 2018, 11:45:36 PM »

For the curious..  these aren't taken with a phone..  mostly Fuji X100T except today I shot a Fuji X-E1 with 35mm f2 WR lens.  It's just like a Leica only not five grand.. ;-)
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Tronman
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« Reply #14 on: April 08, 2018, 01:24:01 AM »

Well I had dreams of getting this bad boy running today..  but nope :-(  Went to reassemble the valvetrain and found 11 of the 12 pushrods hadn't been rotating so they'd worn grooves in their ends and in the rocker arm seats.  Two of the rockers were starting to crack out, even tho the valve heads look perfect and there's clearly no lack of oil in the pivot bearings either.

On the one hand, I'm glad I discovered this now, versus 100 miles away from Mom's house in nowhere, Idaho with a car full of kids and bikes and a severe miss in two cylinders.  On the other hand, now I gotta find a new valvetrain for it.  Crap.
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