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Water pump whoa's

2K views 15 replies 10 participants last post by  T-bucket23 
#1 ·
I'll try and keep this short.
I put a fresh 385 SBC in my 80 El Camino last month. I watched the Dyno and everything seemed fine. After I put the motor in, within 5 miles I blew a water pump gasket, (the left as your looking at it). After I pulled the March serpentine kit off I put new gaskets on and away I was... until another 5 miles then boom, another water pump gasket. The third time it went I figured something else was wrong. It was a brand new Weiand aluminum pump. I then noticed that the pump shaft had about a 1/16 of an inch play which meant after the belt was tightened, the pulley would can't just enough to make the clutch and fan wobble. Would that be enough to loosen those bolts on the left side after three gasket replacements even though I torqued them to 40 lbs each time. Or could something else be creating such a large amount of pressure that it's blowing the gaskets each time? It can't be the thermostat because all that would do is overheat the motor, I have a 3 core radiator that is clean and basically everything under the hood is new with the motor to include the heater core. Has anyone seen anything like this before?
 
#4 ·
For one to build enough pressure to pop the water pump gaskets in that short of a time span kind of spells out something is amiss. It makes it sound like a head gasket is blown and compression is being pushed into the cooling system. However if your sure there is no head gasket or head issues then you can try these things and see if it helps. Drill one 3/16 hole in the thermostat. Remove the water pump and check for sealing surface squareness on the pump and block mounting surface. Make sure you have a vented radiator cap and the bung on the side of the radiator neck is in use and connected to the resevoir.
 
#5 ·
Yep something is screwy, never heard of blowing wp gaskets. What psi rad cap are you running?? most guy's I know use 16#. Is it overheating first then blowing? Is the thermostat installed upside down? If the cap isn't getting unseated by pressure then there must be an issue with the pump sealing surface....but I'm sure you've checked that already. You might try driving it with the rad. cap off, you'll probably puke some coolant so drain a quart or so out first.......watch your temp gauge!! See what happens.
 
#6 ·
All great recommendations. The motor is running a cool 160, of course until the gasket goes and I lose water. Luckily I've been only a few miles from the house and was able to limp it home before it reached 210. I'm pretty sure the head gaskets are fine for the motor has less than 60 miles on it. Though I put the thermostat in myself I'll pull it and double check it, I'll also replace the radiator cap just in case. I'm just frustrated after pulling the march kit off three times and I don't want to do it again. I put a Stewart pump on it last week and warmed the car up but was out of town until last night. Hopefully tomorrow I won't be pulling off another WP!
Thanks guys.
 
#7 ·
I would look at the mating surfaces real close. I would think that there are a lot of things that would fail before that gasket if you had a real high pressure issue. I would expect a hose to blow off or the radiator cap to puke first.

If you dont find anything try a little silicone on the gasket, if there is a small imperfection in one of the surfaces it may be enough to offset it.
 
#9 ·
Number 4!!!!!!
Yes, took it out today, got on it once and blammmo!! Gasket set number 4. Here is what I think is going on. Taking a "real" close look at the pulley, clutch and fan, it still seems to have a slight wobble. At 5500 to 6000 RPM the vibration is so bad that it's wiggling the bolts loose. The common denominator is the bolts have been loose every time I pull the serpentine kit off to replace the gaskets.
Prior to taking it out I bought a new 180 thermostat and a 16# radiator cap, I drilled a 3/16 hole in the thermostat and it still went. Today I installed a Mark VIII electric fan IN the shroud but have not wired it up yet. That takes everything off the water pump so I'm alleviating any chances of vibration. If I have to take the front end of that 383 off a 5th time I'm going to go crazy!
(BTW, the surfaces look perfect and I have used RTV every time, and I'm torqing the bolts to 40~45 lbs.)
 
#10 ·
Are the water pump bolts the proper length? What I'm wondering is that they might be bottoming out, making you think they're tight. I had that happen to me with an aftermarket aluminum Chevy pump that I used on my Hemi. The whole pump wobbled a very little bit, and it took a few minutes to figure it out...while it was on the stand. I shortened the bolts a 1/4" and it tightened right down...
 
#11 ·
By the way RTV is exactly the WRONG gasket maker to be using in these gaskets, it makes them slippery. I went through this exact problem years ago on my race car. Use something sticky/tacky like Edelbrock Gasgasinch, No 2 Permatex, Permatex Aviation High Tack, or even 3M Weatherstrip glue. RTV is meant to be used in place of a gasket, not with a gasket in most cases, or to cover a gasket overlap joint. It is not meant to be a gasket dressing, and is much overused in this regard.

Heed what Dedub said about the bolts also, the uppers on both sides are susceptible to bottoming out. Make sure there is enough thread on the shank to not run out also.
 
#12 ·
I don't think it has anything to do with water pressure.(IMHO) I bought a March pwr. steering pump bracket for my sbc. It replaced the two 2"+/_ bolts that mounted the water pump with much longer bolts that went thru the bracket, 2 hollow spacer tubes, then thru the water pump. I could deflect the pwr. steering pump a bit by hand. I felt that it was to much of a load for the longer bolts to hold it all together, and that the thin wall tube spacers weren't wide enough to spread out the load.(IMHO)
I made some spacers out of 3/4" hex bar stock cut to the same length as the tubes. I drilled a 5/16" hole thru the center and tapped them with an extended length 3/8" tap. I then installed 3" threaded studs into the block
where the pump mounts and used the hex spacers as extra tall hex nuts to hold the water pump on. I then used 2ea 3/8 x 3/4" bolts to hold the bracket
to the hex spacers. I can remove the pwr steering bracket and the water pump stays put, unlike the original bracket hardware. The assembly feels much more solid.
Its my opinion that the tube spacers are made of potmetal and will give a little under load making the bolts loose. For what its worth.
ssmonty
 

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#13 ·
Are the bolts still tight when you take it apart. If they are loosening up due to vibration you could throw a little blue lock-tite on them. Is the gasket actually ripped or is it just leaking past it. I am liking the long bolt theory that someone else brought up. You could simply put a flat washer on the bolts to see if it solves the issue, if it does get some shorter bolts. We use silicon all the time for gasket retention or to make up for pitted surfaces and have had no issues. Most time people use way to much and this is what it fails to work for them. For just gluing gaskets on we use the 3m weather strip adhesive and only put it on the removable part.
 
#14 ·
I had this same thing happen to my water-pump same side also, But at the time it happened i was battling pulley issues i put a new water-pump on after i got my pulleys worked out or lined up anyway. And have had no more problems since, So it turned out my pulleys not being straight was the problem causing a vibration and when under a load popped the gasket IMO.
And i am still running the stock bolts on the pump also.
Cole
 
#15 ·
Hey Cole, I think you and I are in the same boat..std by, more to follow....

ericnova72, I am using RTV but only "very" thin layer, just enough to hold the gasket and no more, basically you can see through it.

T-bucket23, Fact is, the bolts are loose when I pull everything apart, looser than the thickness of the gasket thickness if that makes sense. I have used the red lock tight on at least 2 of the 4 times but that didn't seem to help. Is the Blue more permanent?

345 desoto, I believe the bolts are good to go. At first I thought the same thing, I then added a think lock washer to be sure and I ended up with just less than a 1/2 on the bolts.

ssmonty, Wow, great job on the modification! I may PM you if I still have issues if you don't mind.

OK, i gave up on the whole Clutch and fan. I good friend had a spare Mark VIII electric fan. Last night I cut, chopped, and fabricated until 2300 and squeezed it in my shroud with rivets. Today I bought a universal controller with relay and wired it up. After filling fluids and firing it up again I "think" I'll be OK. Tomorrow I'll take it out and get on it a few times. I IMHO the fan and clutch were off balance and at 5500 RPM it just reeked havoc on the WP bolts thus wiggling them out every time. I'll keep you guy updated.
 
#16 ·
dedub said:
Hey Cole, I think you and I are in the same boat..std by, more to follow....

ericnova72, I am using RTV but only "very" thin layer, just enough to hold the gasket and no more, basically you can see through it.

T-bucket23, Fact is, the bolts are loose when I pull everything apart, looser than the thickness of the gasket thickness if that makes sense. I have used the red lock tight on at least 2 of the 4 times but that didn't seem to help. Is the Blue more permanent?

345 desoto, I believe the bolts are good to go. At first I thought the same thing, I then added a think lock washer to be sure and I ended up with just less than a 1/2 on the bolts.

ssmonty, Wow, great job on the modification! I may PM you if I still have issues if you don't mind.

OK, i gave up on the whole Clutch and fan. I good friend had a spare Mark VIII electric fan. Last night I cut, chopped, and fabricated until 2300 and squeezed it in my shroud with rivets. Today I bought a universal controller with relay and wired it up. After filling fluids and firing it up again I "think" I'll be OK. Tomorrow I'll take it out and get on it a few times. I IMHO the fan and clutch were off balance and at 5500 RPM it just reeked havoc on the WP bolts thus wiggling them out every time. I'll keep you guy updated.
Actually the blue is less permanent.
 
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