: Another pressure test update



bobvondutch
06-16-04, 03:39 PM
First, thanks to Zonie and Eldo1 for last night's tips. I'll let you know what I did today, then let you comment.
1) Remove all plugs, insert pressure test tube in #1, connect home-made pressure gage set-up to tube.
2) Rotate by hand till pressure gage showed pressure building, then removed gage.
3) Inserted smoothed-off straightened coat hanger down through tube, kept rotating and noted when TDC occurred. Wrapped wire with electrical tape so I had a reference for all cylinders. NOTE: I couldn't find a TDC mark on the balancer, and didn't know where else to look.
4) Replaced the other 7 plugs, put the air to her and checked the coolant.
5) REPEATED FOR ALL 8 CYLINDERS. I figure that since Sunday I have performed three Northstar lifetimes of plug changes, assuming you change plugs every 100K. Suprised I don't have to heli-coil the heads!!!
6) Never found any bubbling coolant: only odd thing was that the air rotated the engine when I did #6 & #8 - all the others stayed where they were.

Sooooooooooo..... I'm making an assumption that I don't have a head gasket problem. I'm also assuming that in seven years this engine has never had a coolant change, even though there's only 80K on it. So my plan of attack is this: new set of plugs (owners manual calls for AC41-900 ... anyone have any other recommendations, and what is the gap?), new thermostat, new water pump and drive belt, remove and check the tensioner, making sure it's still good, new 50/50 coolant, two bars leaks tubes, fire it up and run the snot out of it!!!!

Good explanation in the back of Car Craft that came today about coolant/distilled water/de-ionized water: basically that freezing properties remain when coolant wears out, but boiling properties go to hell. As usual, BBob knows his poop, as that is what he told me in the first place. Anyhow, I figure I'll take the dealer up on his offer and get the head gasket set, the time serts, and all other gaskets since he thinks it's a head gasket and that I'm going to fix it - if I never need it, Ebay is a wonderful thing.

I'd appreciate any and all comments - does everyone else think I'm right, or should I recheck #6 & #8, or check something else?? First run will be to the NSRA Goodguys show in Ohio, July 8-11, and we'll see how it goes. Again, thanks to everyone.

Oh, one other thing. On the front (?) of the engine, attached to both the engine and near the radiator, are two dog-bone shaped brackets, with rubber mounts. Are these simply for torque purposes?? How much play is acceptable?? These things move around by hand, and it ain't the rubber - I'm talking at least 1/8" movement. Thanks.

eldorado1
06-16-04, 04:41 PM
Sooooooooooo..... I'm making an assumption that I don't have a head gasket problem. I'm also assuming that in seven years this engine has never had a coolant change, even though there's only 80K on it. So my plan of attack is this: new set of plugs (owners manual calls for AC41-900 ... anyone have any other recommendations, and what is the gap?), new thermostat, new water pump and drive belt, remove and check the tensioner, making sure it's still good, new 50/50 coolant, two bars leaks tubes, fire it up and run the snot out of it!!!!
Sounds like a plan! As long as you didn't hear any air leaking out anywhere on #6 and 8, they're probably fine.



Oh, one other thing. On the front (?) of the engine, attached to both the engine and near the radiator, are two dog-bone shaped brackets, with rubber mounts. Are these simply for torque purposes?? How much play is acceptable?? These things move around by hand, and it ain't the rubber - I'm talking at least 1/8" movement. Thanks.
They call those dog bone mounts :rolleyes2 If the rubber on them is fine, they're probably fine. However, you may want to check the other mounts where the engine attaches at the cradle if you're seeing lots of movement.

zonie77
06-16-04, 04:42 PM
I made an assumption about the TDC mark, maybe it isn't on there!

I've done 2 N*'s. 1 showed on the compression test, the 2nd was previously diagnosed as bad head gaskets so we just dived in.

The first one took a long time to diagnose because it kept acting like a straight forward overheating problem. Eventually a combustion test by a radiator shop was positive and the compression test verified it, but none of the cyls were real low. I think about 30 lbs lower than the others. I would not tell you to change the head gaskets without evidence of them being bad but I will add that they have to get pretty bad to show on a test. Did you see the pics on the info page I did? They didn't look that bad when we pulled them apart. The head/block surface was cleaner where they were blown, that was it.

Your plan to take the parts and wait & see is probably the best at this point.

bobvondutch
06-16-04, 05:54 PM
The only air I heard on these cylinders was coming out the exhaust. When they spun, it must have opened up the valve. It was coming out, but not real forceful so I just checked the coolant for bubbles.

zonie77
06-16-04, 06:38 PM
It will take awhile for the bubbles to show. They have to travel to the overflow so guesstimate how long that might be. You might notice the level start rising in the overflow first.

That reminds me of another thing you should try. When the engine is warm try cranking the engine over without starting it. Watch the coolant in the overflow for a rythmic surge. If a head gasket is leaking you should see that surge.

bobvondutch
06-16-04, 07:23 PM
I would think that at 120 PSI, it wouldn't take more than a couple of seconds to see any movement at all. There's a sort of scum on the surface, and it never wavered unless I bumped the car during any of the testing.

zonie77
06-16-04, 08:49 PM
If you didn't see any movement I'd hate to tell you to pull the engine. I'd drive it awhile longer and see if the problem gets worse. I know that doesn't give you a warm and fuzzy feeling but the headgaskets are a lot of work.

Try watching the overflow,cranking, when it's hot. You'll have to drive it or warm it well with the cap loose.

Good Luck!

BeelzeBob
06-17-04, 03:14 PM
The pressure test has yet to fail me when checking headgaskets....so...if you put 120 PSI to each chamber and held it for 5 minutes or so and saw no bubbling or movement of the coolant in the surge tank I would give your head gaskets a clean bill of health. Make sure the rest of the system is good like you indicated and go from there.

The NEXT time you do a pressure check of the combustion chambers it will be much easier, right...???? This is called "experience" and is the most valuable commodity around....

BeelzeBob
06-17-04, 03:17 PM
BTW...you also want to check the flow out of the vapor vent line to the surge tank if I didn't mention that before. Take the 3/8 hose off the surge tank, start the engine when cold and coolant should pee from the 3/8 hose. If not, trace it back and find the obstruction. If the pump cannot vent then it will lock up and will not pump and it will overheat.


IF the water pump is not leaking....why change it...??? I would certainly do the water pump belt and water pump belt tensioner (and check the vapor vent line) but the pumps only real failure mode is leaking seal and then noisy bearing..if OK now then it should still last a long time.

eldorado1
06-17-04, 04:18 PM
start the engine when cold and coolant should pee from the 3/8 hose.
Is that one of your crazy-engineering-technical-terms? :D

dloch
06-17-04, 06:30 PM
Is that one of your crazy-engineering-technical-terms? :D
Yes, if the flow is low it's pee. If you leave the hose off and race the engine up it's piss. Another another well used term is P.S.O..... Pressure Squirting Out. :rolleyes2 You really don't have a head gasket leak you really have Pressure Squirting Out :helpless: . Not to be confused with P.F.O. Parts Flying Out. You generally get that when you have defective oil pans or the side of the block is not strong enough to hold everything inside. :hmm:

bobvondutch
06-17-04, 06:37 PM
Bbob:
When I did the pressure test, I only let the air connected for 30 seconds or so, the time it took to beat the flashlight batteries into working and taking the rad cap off. Like I said earlier, I was looking for movement also in the coolant and saw none. SOOOOOO...based on what you said it sounds like I should run the test again and let it sit longer. Problem is the K-D adapter is a straight thread, doesn't seal like the tapered seat on a plug. If I tightened it down to seat, it would ruin the first thread in the head. Need an opinion - run it again or not??? As far as the water pump, I was only going to do it since I had everything drained but I had no noises or leaking before. There was a good article in Car Craft tech forum, said that antifreeze over the years loses it's ability to aid in heat transfer but not it's ability to prevent freezing. I'm assuming that in seven years, this coolant has never been changed, never had tablets or powder added. Let me know on the test rerun, and thanks again.

BeelzeBob
06-17-04, 11:45 PM
30 seconds is really border line for a conclusive test. You didn't have a really bad head gasket leak but the idea of the test is to let the pressure sit for several minutes at least to see if any seepage starts coming past the head gasket.

Now that you are so good at it I would rerun the test to make certain.

Use an old plug and make the proper adapter. Just squeeze the porcelean in a vise to break it up and then beat the porcelean out of the plug shell. If you take a grinder to the rolled rim on the outer edge of the plug shell (that radius above the hex area) the porcelean will come out that side much easier. Drill and tap the shell for a pipe nipple and use that instead. It is really pretty easy to make one. Then it will seal and you won't have to worry about the threads at all.


That car craft article was a bit misleading if you read it very carefully.

What they were trying to say was that the coolant is basically ethylene-glycol that doesn't wear out. JUst the additive package in the coolant that serves as the corrosion inhibitor wears out. The ethylene-glycol provides the anti-freeze and anti-boil properties. That never wears out. The corrosion inhibitors get used up , however, so the coolant needs to be replaced. The corrosion inhibitors in the additive package have nothing to do with the anti-freeze or anti-boil protection. That is purely the EG. The article says this, basically, but not very clearly. It kind of jumps to the idea of the additive package and then mentions the anti-boiling protection. Not very clear.

The conventional green coolant and the DexCool coolant are both ethylene-glycol so there is no difference in them from a freezing/boiling standpoint. The green stuff uses silicates to prevent corrosion and the DexCool uses an organic acid based corrosion inhibitor. THAT is the difference in the coolants. The silicates deplete with time and use so the green stuff needs to be replaced frequently to keep the corrosion inhibitors at full strength. The DexCool corrosion inhibition capability remains the same for very very long periods of time hence its long life moniker.

Nothing about using the coolant or not changing it affects the anti-freeze or anti-boiling protection as the EG never wears out or fails...just the corrosion protection. The "heat transfer" characteristics also do not change as long as the percentage of EG remains the same. The heat transfer capability of the coolant is based on the mixture ratio of water and coolant in the system. The additives have little or no affect on this.

Did you see the article on the EGR at the end of the Car Craft tech section. I know the guy that wrote that....LOL.

bobvondutch
06-18-04, 12:31 AM
OK, you win - I'll do it again. One quick question though: was I correct in finding TDC for each cylinder, then putting the plugs back in?? I can't think of another way to hold the crank from turning. At that rate, I'll need to heli-coil the spark plug threads!!! Knew I shouldn't have put that front wheel back on this morning!! Took it down off the stands too!! Hey, live & learn --- thanks again for the help.

eldorado1
06-18-04, 02:17 AM
OK, you win - I'll do it again. One quick question though: was I correct in finding TDC for each cylinder, then putting the plugs back in?? I can't think of another way to hold the crank from turning. At that rate, I'll need to heli-coil the spark plug threads!!! Knew I shouldn't have put that front wheel back on this morning!! Took it down off the stands too!! Hey, live & learn --- thanks again for the help.
When you're in the correct spot (TDC compression), there will be NO air leaking out ANY valves. I would get a helper and a cheater bar with the correct socket to hold the bolt on the pulley while you pressurize each cylinder. Good luck man, we're rootin' for ya.

dloch
06-18-04, 11:34 AM
Did you see the article on the EGR at the end of the Car Craft tech section. I know the guy that wrote that....LOL.
Yes I did. That was quite informative. I also liked the article about V8 version of the CTS...

Ranger
06-18-04, 05:16 PM
Bill,
That being the case, why do we change coolant? Wouldn't it be more economical and environmentaly correct to just add a can of corrosion inhibitor every few years?


What they were trying to say was that the coolant is basically ethylene-glycol that doesn't wear out. JUst the additive package in the coolant that serves as the corrosion inhibitor wears out. The ethylene-glycol provides the anti-freeze and anti-boil properties. That never wears out. The corrosion inhibitors get used up , however, so the coolant needs to be replaced.