[tfaubus]

Hello people,
I have recently gone from a minor leak of coolant to more severe. The intake set probably didn't seat just right the last time I changed 'em but I planned on swapping them again in a few weeks. EXCEPT, now I got a rattle...
Not sure how bad it is but sounds like top end, non-timing chain or belt related, and it came on rather suddenly. It wasn't there the previous night but was very noticeable the next morning at temperatures near freezing but I know I have kept the coolant full and bled and the oil has been fine as well. I suspect it's possible I got some coolant in the oil but not noticeable on the dipstick by level or color. There is coolant on the top of the engine enough to steam so no I'm not driving her for now but I am trying to decide on whether I should go ahead and really tear into her or just buy a reman long block and swap the whole darn thing. The trans, body, paint, interior and the new headlights I just got all look sweet so I can't imagine I'd scrap her.
I am thinking I'll go ahead with the intake gasket set swap since I already have the parts and totally drain and fill both the coolant and oil. Then I will have a solid point to move forward from with some diagnostics. I am told there was a check engine and low oil level light but it turned back off and didn't come back on. Like I said, the fluid levels were fine though.

Opinions?
THANKS!

This post has been edited by tfaubus: 21 February 2010 - 06:36 PM

[tfaubus]

Ok, took it all apart today and of course, found coolant all over the top of the engine even though I drained it beforehand. The lower intake was leaking but not damaged or deformed in any way, the t-stat was fine and the rad cap too. So, I'm going through with the gasket swap but I was thinking I should try to find a new set of lower intake bolts. Those seem to be hard to find though anyone got a source?
Also, maybe my torque pattern could be better but I criss-cross from center out in pretty consistent increments so I can't imagine I could do it better to prevent leaks again. Anyone try RTV in this area? Maybe some thread locker on the bolts?
This is like the 5th time I've had to do this and I would like to not have to do it again for a while.
Once I put it back together, I'll do a good oil and filter change before running it to op temp and trying to locate the rattle.
If anyone's bored or smart with this please chime in.
Thanks!

This post has been edited by tfaubus: 11 February 2010 - 11:55 PM

[me6894]

Can't say for sure about the DOHC, but on every motor I've ever done intake gaskets on you need sealer on the bolts!! Make sure they are cleaned good and use pipe sealant or even rtv if you're in a bind.

[tfaubus]

me6894, on 11 February 2010 - 11:25 PM, said:

Can't say for sure about the DOHC, but on every motor I've ever done intake gaskets on you need sealer on the bolts!! Make sure they are cleaned good and use pipe sealant or even rtv if you're in a bind.

I hear ya but I've never needed it here. The bolts have always stayed tight and never showed any signs of rusting. I used it this time for GP but doubt it makes a dif.

But, to continue my saga, I went ahead and basically cleaned and reinstalled my entire intake system to fix the coolant leak. At the very least, my garage smells of hot rod . I replaced the injector seals, cleaned and re-oiled the air filter, and replaced a couple of vacuum tube connectors that were weathering. In the process I put a bead of RTV around the water ports of the lower intake seal before putting it back together. I was examining my lower intake bolts and I though about replacing them but the lowest I could find was $5.13 ea on GM Parts Direct x 12 plus shipping = 78.51!! No way. OK, so they are a sandwiched rubber/metal assembly that contacts metal on the bottom and top but not in the middle. The end result is a little compression system. SO, AFTER A WHILE IT SMASHES AND WON'T HOLD A GOOD SEAL!!! SOLUTION- take an extra set of injector orings which are thick and just the right size to fit under the spacer making direct contact with the lower intake for a much tighter install. Guess what, no more leak...

So, as I am finishing up I put a little Marvel Mystery oil in each cylinder to hopefully counter act the carb cleaner I sprayed in there. I added some gas treatment to the tank, did an oil change with some Valvoline High Mileage 10w-30 and a PureOne filter. Before lighting the fires I disabled the spark and fuel and spun the engine a few times to ventilate the cylinders and let it set overnight. In the morning I ran it up and it smoked like a pig but cleared up while I bled the coolant sys. The noise was still present and I let it keep running and I figured if it's going to break, screw it. But it didn't. As it warmed up I noticed it was on the side of the belts and timing chain so I pulled the front cover and took a look. Everything looked great since I just changed the timing belt and idlers 14000 miles ago. The interesting thing was the sound was directly in time with the cam rotations so I figured it was the timing chain.

As it warmed up the noise gradually went away.... Hmmmm
To be sure I didn't get my hopes up too early I let it fully warm up, double checked for leaks, made sure I had good coolant flow from the bleed ports, and then shut it down and let it sit all day to thoroughly cool. I just got done checking the fluids, topping up the coolant and everything looks great. So, I start it up hoping the noise is gone,... and it is,... gone. Whew!
Guess it's back on the road.
LOL!

PS I used a quart of Gunk high mileage engine flush too. I might have went a little overkill but, what the hay, why not.

This post has been edited by tfaubus: 15 February 2010 - 11:06 AM

[tfaubus]

 DSCF3003e.JPG (366.1K)
Number of downloads: 41
 DSCF3027e.JPG (229.01K)
Number of downloads: 39

Here you see everywhere coolant is not supposed to be plus the orings I used to fix it.

This post has been edited by tfaubus: 15 February 2010 - 11:15 PM

[tfaubus]

tfaubus, on 16 February 2010 - 12:14 AM, said:

DSCF3003e.JPG
DSCF3027e.JPG

Here you see everywhere coolant is not supposed to be plus the orings I used to fix it.

Anyone else having trouble pulling up the photos now?
What's the dealio?

[NiftyMonte]

i can see them

[tfaubus]

I am getting an error every time in IE8 and Firefox:
[#10173] We could not find the attachment you were attempting to view.

It was working before but not anymore and the help documentation is not helpful.

Any admins out there that know what's going on?
I tried to attach a screen shot but got an error with that too. I haven't posted many photos so I am confused.
Thanks!

[Cully77]

I can see the thumbnails but it's not pulling up the photos.

Do you have a photobucket account? I find it easier to use the IMG tags rather that always attaching photos.

[tfaubus]

Cully77, on 20 March 2010 - 12:10 PM, said:

I can see the thumbnails but it's not pulling up the photos.

Do you have a photobucket account? I find it easier to use the IMG tags rather that always attaching photos.

So, now they decide to work again, sheesh.
Maybe I'll look into the photobucket idea.

[Dave96Z34]

What did you add to the lower intake bolts? They should just be bolts nothing more. If you tighten them down correctly in the correct pattern you wont get a leak you just gave it room to move once the rubber finishes crushing out you will be screwed all over again. No reason to change what works you just added another point of failure.

This post has been edited by Dave96Z34: 21 March 2010 - 09:15 PM

[Dave96Z34]

double post

This post has been edited by Dave96Z34: 21 March 2010 - 09:15 PM

[tfaubus]

Normally I would agree that adding something to the bolts would add another possible point of failure. BUT, the bolts aren't just bolts, they have a built-in (pressed on?) metal/rubber bushing which has compressed over time and you can't just swap out the bushings. I only added more rubber/poly so that it would seal better and I am sure it will last longer than the bolts as they were. And, replacing the bolt assemblies with new ones is not a cost effective solution. I am also not a fan of slopping on a bunch of gunk to try to help seal it either. It has to handle 15 PSI of pressure or it's no better than the radiator cap.

Going with just the old bolts/spacers is what gave me the leak to begin with so I had to do something different. The torque spec is a non-issue, already got the t-shirt years ago on that.

I am confident now after driving almost 500 miles that my problems are over for at least the next year or so.
I called my local chevy parts dept and they said the bolts are being discontinued so that presents a problem as far as long term solution is concerned too. But, I take any and all statements from parts counter people with a grain of salt and verify by second opinion wherever it makes sense.

For the record, I have had this thing apart probably 5 times now and there are no other defects to note except these bolts not holding enough pressure to keep a good seal. How it works is the key. The base of the bolt head bottoms against the top bushing. The bottom bushing is what holds pressure against the lower intake. There is only rubber that transfers the downward pressure from the top bushing to the bottom bushing. Adding a thick o-ring under the lower bushing effectively increases how much overall pressure is available to keep the seal. Because the lower intake holes are countersunk, there is less potential for the o-ring to expand outward and therefore my engineering conclusion was, try it and watch it, nothing to lose.
And I'm never wrong dang-it.

[Dave96Z34]

No what im saying is those are not the stock lower intake bolts. This is the stock lower intake bolt. The same ones that I use to keep my lower intake rock solid from the blower belt torq with no leaks. Looks like some one had an idea and now your paying for it.

[tfaubus]

Now THAT is an interesting revelation! I bought the car NEW in March 1995 and it has been to the dealer exactly ONCE for the lower intake seal problem. Is it possible they changed the bolt spec from 95 to 96? I don't believe I have ever read anything about changes to the lower intake only the upper for 96. I doubt the dealer switched the bolts and due to the price they charge I think 96 and newer just has different bolts. Which is better or worse I suppose is debatable. The bolts you showed probably eliminate the rubber compression problem but if the stress points aren't exactly right then maybe that explains why some have busted gaskets. Nice.
See the attached picture, I bet the holes that the bolts pass through are smaller on 96 and up.
But mine's a 95, no doubt about it.

Attached File(s)

•  DSCF3022e.JPG (246.76K)
  Number of downloads: 15

[Dave96Z34]

Wow the holes on that lower intake are huge. 96 97s its the same size bolts as the upper intake. Im not 100% shure about 95s but thought they were the same. I have pics of other 95s at my house all check when I get home.

[Dave96Z34]

Looking at the pics I have 91-95 has your kind of bolts. The prob you are having is probably why they revised it in the 96-97.

[tfaubus]

Yeah, well if it happens again I'll find a set of con-caved washers and some more orings!
Adapt and overcome I tell ya!

[Dave96Z34]

lol nice
Hey if it leaks again should consider going to the 96-97 plenum. They are getting easy to get a hold of and can make 10+ more hp easy.