Hello all,

I am enduring a rather frustrating issue involving my cooling system. I have been dealing with the passenger side water pump gasket continuously blowing out after i hit about 5300 RPM on a full throttle rip. I have exhausted about every solution my young mind can come up with-(Replaced water pump, Checked block-to-pump mating surfaces for cracks, burrs or loss of squareness, Tried different brands of gaskets, New bolts, Experimenting with Hi tac sealer for gaskets which made no difference, Re-installed coolant bypass hose between water pump and intake and teflon taped the W/P bolt threads). I have yet to try another thermostat, although the one I have installed is a brand new 180 degree unit. Engine is a stock bottom end LG4 with World S/R torquer 305 heads, Crane cams 2040 camshaft, Edelbrock performer intake and a set of hedman headers, so 5300 RPM shouldn't be an issue for it. I'm thinking the cooling system is obviously over pressurizing, yet I am out of ideas at the moment.

Any knowledge and/or suggestions are much appreciated!

Thanks!

 

might have to take a punch and make some little dimples in the gasket mating areas to help hold the gasket in place.Also make sure you tighten the pump bolts very evenly.Pressure buildup not really a factor as hoses would blow off before that gasket pushed out(if everthing was right with it .)

 

The only thing you haven't changed is the block. That's a strange problem. Maybe your bolts are bottoming out (crud in there?) and you aren't really torquing the pump tight enough? Those hoses would go way before the gasket. Check those bolt holes

 

I will look into it on Wednesday. They are torqued evenly at 30 ft-lbs as per the specifications. I was sure i cleaned all the crud out with the engine on the stand when it was getting rebuilt, but it's always possible something was missed, as this is my very first engine build and am still learning.

Maybe it's also possible that it really isn't square on the mating surface as it seems to leak from the same very specific point... Weird, but it never hurts to check again.

Thank you both for your time! It helps more than you think

 

To add to what Tootie said, if some of your WP bolts are too long, they can bottom out and you would think they are tight when they really aren't.
A few of those bolts, if too long, can actually bottom out against the outer cylinder wall.
My truck was doing something similar years back and only the FelPro blue stripe gaskets stopped it.

 

I've went back to using the stock bolts as of now due to hearing about that issue, they shouldn't be too long should they? Weird if they are...

And those are the gaskets I have been using. Same problem has returned

 

Have you tried a thermostat with a bypass in it? You can drill a couple of small holes in the one you have now if you don't want to buy a new one. I have a Stewart in mine, it has 3 bypass holes in it, so coolant is always flowing through to the radiator. Not sure if that will fix it, but that might help.

https://www.summitracing.com/parts/emp-301/overview/

 

Will definitely try that out as well. Thanks for the suggestion!

 

Good suggestion, but he already has a large bypass - that heater core bypass hose from cylinder #2 back to the water pump inlet.

 

I'm sure you have checked but what shape is your radiator cap in? If it is not releasing pressure at it's designed psi, it will eventually find an exit somewhere.

 

Did you use rtv on both sides of the gaskets?

 

Yes, I've tried gaskets with a thin layer on both sides, and more gaskets that were installed dry. I'm leaning more towards an issue with the block mating surface that I will need to investigate because it leaks out of the exact same spot every time.
Radiator cap is also new, but it could very well be defective. I'm going to replace it when I have everything apart tomorrow, as I'm doing over the front accessory drive system.

 

While you have it apart, lay the water pump on an extremely flat metal surface on the mounting surface and check that it is true as well.

 

Will do. I'll keep you all updated.

 

I noticed that when I had the water pump replaced on my 03' vortec that a aluminum gasket was used. I can see it. Not sure if they make these for SBC's but the thing sure has not leaked in about 3 yes or more mow.

 

Hm... maybe I could try and find a stronger gasket then?

 

I had that same problem a long time ago on my old 73 nova w/350,when I would spin it past 5500. I put the gasket on dry(no sealer) and that fixed my problem,but I read that you tried that already.
I would pull the pump and clean both sufaces and put some prussian blue/marking compound on the pump and install it without the gasket..then remove it and see if the surface is warped.

 

I bought myself a rotary tool and used a very fine sanding disc to resurface both the block and pump mating surfaces. Checked with a straightedge and both were square. Reinstalled water pump with new gaskets and added lock washers to the bolts (used to have no washers). Also purchased a new 180 degree thermostat with the three bypass holes in it to help with pressure buildup in the block. So far no leaks yet, but I managed to break an axle shaft the day after I got it back together (figures, right? lol) so I'm working on that project for the time being.

 

Sounds to me like you probably didn't have all the old gasket material/sealant off the block and it was causing uneven gasket clamping force. Perhaps with the new rotary tool dressed surfaces you will have more luck.

GD

 

Hoping so.... Fingers crossed!