Help! Coolant leak

Chuck · 12-28-08, 09:50 PM

Coolant Leak

Can’t locate the source of a persistent leak on our 302 with a short water pump. Only have a few hours and less than fifty miles on the motor. It was free of leaks at Run and Gun in October, than sat a month without being run. Fired it up and noticed a leak but can’t find the source.

Coolant puddles in the valley on the left top of the water pump. When the engine is shut down it will disappear. There is what appears to be a threaded hole in the base of the valley. After the engine is shut down I assume the coolant drains through that hole after it has collected in the valley, but where is it coming from?

Have not removed the fire wall yet. The bolts on the water pump that can be reached from the side are secure. Removing the fire wall will be the next step, but wanted to make sure I was not overlooking something obvious.

I am not familiar with the internal workings of the water pump on a 302. Was wondering if a gasket could be seeping coolant. Perhaps a gasket got dry setting for a month? Are there any leak issues with these short water pumps?

It is not the thermostat cover. If it were leaking the coolant would collect on the opposite side. All coolant hoses are tight.

The amount of the leak is small. Perhaps a half to one cup in thirty minutes of run time. The day after running the engine a puddle the size of a couple of silver dollars was on the garage floor.

Pics attached taken from the left side, showing the coolant collected in the valley, as well as dry. The threaded hole is visible.

Steve C · 12-28-08, 10:30 PM

Chuck,

As I recall some of the waterpump bolts require thread sealant as they pass through a coolant chamber. I notice that the puddle is in the cavity where a threaded hole is located. Suspect that bolt wasn't adequately coated prior to install?

Steve P2125

Jac Mac · 12-28-08, 10:57 PM

More likely to be an incorrectly fitted or wrong gasket combination for the application. Non of the WP bolts require thread sealant if the correct gaskets are used & the pump & back plates have no corrosion.

Chuck · 12-29-08, 08:31 AM

Sounds like we pull the pump and replace the gasket. Any gasket recommendations? Better to use sealant with the gasket, or not?

Randy V · 12-29-08, 10:16 AM

Thru bolts that go all the way through to the block "should" have teflon thread sealant (same stuff you used on Head Bolts and Flywheel bolts) on them.

I would replace the gaskets and use a thin coating of Permatex's Right Stuff on them. With Right Stuff you don't even need gaskets, but without them, it's a real bugger to get pieces apart if you should need to..

BOB JONES · 12-29-08, 10:49 AM

Hi Chuck,
I had the very same problem with my rebuilt 302. It was due to a warped thermostat housing which could not be sealed with the standard flat gasket type. when I changed the complete housing for the type that requires the 'O' ring gasket the problem was solved.Best of luck Bob.

Chuck · 12-29-08, 02:02 PM

Randy: I note you are a fan of Right Stuff. Guess I need to try it.

Bob: I had the same problem with the previous thermostat cover. Replaced it with a gorgeous turned ally with the the O ring seal. It is sealed tight and no leaks from it.

I am thinking it is a water pump gasket issue, seeping out the top and collecting into the valley on the side of the water pump.

Any particular brand or type of gasket better than another in this location???

Rick · 12-30-08, 12:21 AM

Chuck:
Sometimes the bolts on either side of the transfer holes in the front cover have to be snugged down an additional amount to seal the gasket between the block and front cover. Since it is below the upper level of coolant (below manifold and heads etc) coolant will pool in this area. Try retightening the bolts that secure the water pump with extra attention to those four extra long bolts, you may want to pop a couple of these tablets. eBay Motors: AC Delco Coolant Stop Leak (item 190270572975 end time Dec-30-08 08:43:53 PST)
It is common procedure at GM Dealerships to pop a couple in to any engine that has had the top end opened up for gasket replacemet. It helps prevent leaks and comebacks and will not clog the radiator.
Also be sure that either the manifold or the thermostat housing has a machined step to allow the thermostat to register in it. If both are flat without the recess the housing will not seal.

Mick · 12-30-08, 01:24 AM

Chuck had a similar problem on my 302. the leak was actually coming from the the edge of the intake gasket around the water jacket on one of the heads (not enough sealant around the port) ran down and collected in the pump valley. This evaporated after a drive and the gasket sealed up with heat enough to prevent a significant cooloant leak. It was more noticable when the engine cooled and got worse and worse. In the end had to pull the intake manifold and fit new intake gaskets with good sealant around the water ports. No problem since.

Mick

Jim · 12-30-08, 10:18 AM

Chuck, I agree with Mick. Most likely it is the intake manifold gasket. This is a common problem on the small block windsor family engines (260, 289, 302, 351). Take your time when putting the intake on. Make sure everything is clean and true. Maybe you can use some long bolts with the heads cut off as "guides" when putting the intake back on (not sure if there are any bolts that go in straight) maybe the center 4 do. This will keep everything lined up. Also don't use the cork end seals use RTV instead. Hope this helps.

Chuck · 12-30-08, 11:13 PM

Found the Problem - Now need a solution

We rented a Coolant Leak Tester Kit at Auto Zone for $150. But the deal is we get a full refund when we take it back. What a great deal!

Hooked it up and in one minute we found the leak.

It is the threaded hole in the forward portion of the valley on top of the water pump. It started coming out of that hole with only about five pounds of pressure.

I have no experience with Ford water pumps. Before I start tearing things apart, does any one have any ideas about what is going on?

Is it a gasket problem? Why did the leak start after several hours of running? Why is that threaded hole there? Is this a manufacturing issue? Or an engine build issue?

I retightened every bolt I could reach without taking off the firewall, which will be the next step.

Mick · 12-31-08, 03:25 AM

Loctite thread sealant should stop the leak.

mi

Rick · 12-31-08, 03:54 AM

Is there a bolt securing the water pump that is currently in the hole? If not, it is possible that you have a front cover that is intended to be used with a different water pump, causing an internal leak. I went out and on my early 289 and assorted spares there is no hole in that area.

Dimi Terlecky · 12-31-08, 06:27 AM

If you can determine that there is no coolant leaking internally and it is only leaking to the outside the easiest way to seal this provided the hole is threaded is to insert a hexagonal headed grub screw of the right diameter into the hole from the outside making sure to use Locktite on the threads before screwing in.

This will seal the hole and save you the job of having to dismantle the front of the motor.

Eventually when a future service or rebuild is required you can rectify the problem permanently.

All the best

Dimi

Chuck · 12-31-08, 10:33 AM

Thanks for the suggestions.

Rick: the hole appears to be around 1/8 to 3/16" so I don't think it is related to the bolts securing the water pump, but I will double check. That is a good thought.

Dimi: I like your idea and may give that a try. The hole does appear to be threaded, but is hard to get to.

I am still puzzled by (1) why is that hole there and (2) why is it leaking? Makes me wonder if (1) if the gasket is the wrong type or faulty, or (2) some guy on the assembly line got carried away with his drill press. I just don't know enough about this water pump to know.

Sure seems like an odd place for a hole.

Keith · 12-31-08, 11:16 AM

Chuck,
It sure looks like the end of a threaded hole for a water pump bolt. Is there a bolt on the water pump that lines up with it? If there is a bolt that is in the hole the solution just may be as simple as removing the bolt, cleaning the bolt and the hole and reinstalling with sealant.
If there is no bolt, and you are sure you have a waterpump that will work with your timing cover, the fix would probably be to remove the waterpump and "plug" the hole. If it is a waterpump bolt hole you could cut a short threaded portion off a 1/4-20 (that is what it appears to be) bolt then use a hacksaw to cut a "screwdriver slot" in the threaded plug and thread it into the hole with sealant. A socket headed set screw would also work if you could find one the correct size and length.
This engine block has been around for a long time so there are a lot of different timing cover/waterpump combinations.........some that work together and some that don't.
Keith

Randy V · 12-31-08, 11:19 AM

I know what the hole is...

First a little background.

Ford decided to take a weird approach (as compared to the rest of the world) to sealing up their water pumps.

The earlier design (as opposed to the shorty late designs common to the Explorer and newer Mustang 50) has a steel plate that seals the back of the water pump.
That steel plate has only two areas that are to be sealed to the timing cover - the two large ports that pass the output of the water pump through to the front cover and ultimately the block.
If either of these two ports do not seal properly, the coolant will get between the steel plate and the timing cover. If not for the weep holes (probably used to detect leaks as well as relieve any air pressure changes in the chamber) - the coolant would build up in the chamber. This could ultimately cause the chamber to corrode and coolant to spill into the crankcase.

So - I believe that what you'll need to do is remove the water pump and replace the gasket that goes between the steel backer plate and the timing cover. Might be best to replace both gaskets.

Yes - Right Stuff.. No leaks..

andy loveday · 12-31-08, 11:58 AM

Hi Chuck, had a look at my front cover and pump, sent you a pm, all best Andy

Dean Lampe · 12-31-08, 12:44 PM

JB Weld!!

Chuck · 12-31-08, 11:03 PM

Randy Nailed It

It has been 35 years since I changed the one and only water pump I have ever changed. So we were not looking forward to this job. But it came together without incident.

Big Foot, (Randy), nailed it. The gasket had torn. Although not a forensic reconstruction mechanic specialist, it seemed pretty obvious to me that one of the bolt hole openings in the gasket was not centered over the hole, had not been trimmed, and the bolt twisted the gasket when it was cranked down. When we replaced the gaskets we carefully trimmed the excess gasket around the bolt holes to match the backing plate. At least that won’t happen again.

Tomorrow, New Years Day, we will fill the system with antifreeze and cross our fingers that this little challenge has been resolved.

The tear in the gasket was permitting coolant to fill the chamber between the backing plate and the timing cover. When it reached the level of the hole in the valley it seeped out. The rust on the back side of the backing plate indicates that this had been going on for some time, but apparently grew worse with time.

Per Randy’s suggestion, we tried Great Stuff on the timing cover side. A nice bead was run around the openings on each side as well as the adjacent bolt holes.

Of course the gaskets were replaced on both sides of the plate. As an aside, when they ask at Auto Zone what kind of car it is, don’t say “1966 GT-40.” The salesman’s eyes will glaze over and he will say “huh?” Instead tell them you need a gasket set for a 1985 Thunderbird 302 with fuel injection. It used the same gaskets as needed for this project.

Thanks for all the ideas and suggestions. Randy gets a gold star.