water pump bolts

[Carl R.]

I have a "62"that the water pump mounting bolts keep coming loose after about two to three months of driving. It starts to leak fluid which then tells me it's time to tighten them again. I have changed from the cork gaskets to the solid type of gasket material with gasket sealant, and new lock washers, but they still get loose. I also tighten them to the book spec of 35 lb. Is this a normal thing since the pump is mounted on the front engine plate? If not, what is the fix for this problem.

[Joseph L.]

Re: water pump bolts

That is a C1 but it seems very excessive. They do work themselves loose at first but not once the gaskets set and are broken in.
You may have oversized block threads? That can happen from retapping the water pump holes with a regular tap, not a thread chaser tape. You may be able to use a threaded rod with the weak loctite, washers and nuts? That way, the thread issue is eliminated.
Joe

[David B.]

Re: water pump bolts

What you describe sounds like a problem that first became prevalent while testing at Sebring in 1956. Ultimately it was determined the front mounting bracket (between water pump & engine) was too rigid causing the leakage of coolant fluid. The solution was to simply cut away a small portion of the lower part of the mounting bracket making it less rigid. This simple modification eventually entered into production on all C1 engines. I think I still have the scratch pad hand written note showing where to cut out. I do not know if this is your problem now but it is an opportunity to relate an interesting tidbit of Corvette history. Regardless this problem should have been solved long ago. Good luck!

[Keith R.]

Re: water pump bolts

Just so happens that the same thing happened recently on my '60. I developed a leak at the upper driver side bolt and it got antifreeze all over my nicely detailed engine compartment! I found that my bolts were loose and considered just putting Permatex high temperature thread sealant on the bolt threads and tightening them but I decided to pull the whole pump instead so that I can clean up the front of the engine. At the same time, it gives me the opportunity to install the correct timing cover screws and the right pipe fitting in the water galley just above the upper heater hose. I've read threads recommending against the use of locktite on the bolts so I'm just going to chase the threads with a thread cleaning tool and use the thread sealant. In a previous post, John Hinckley advises also to bottom the bolts loosely in the mounting bracket holes and then lifting up on the passenger side of the bracket while pushing down on the driver's side before torqueing the bolts down to counteract the rotational force of the engine.

[Carl R.]

Re: water pump bolts

Thanks for the replies Joseph, Keith, and David. This helps to show that I am not crazy or alone with this type of problem. Keith's pictures show the very same thing that is happening to me. I guest I will have to pay more attention to those bolts on my regular check over of the car going forward since this looks like it will be an on going problem. Thanks again for the help.

[Jim L.]

Re: water pump bolts

A friend with an RPO 684 '57 vintage racer had the same problem of the bolts working loose.

He solved the problem once and for all by replacing the stock split washers with high collar split washers. The high collar washers do a much better job of preventing the bolts from loosening.

A web search will turn up multiple sources of high collar washers.

[Keith R.]

Re: water pump bolts

Didn't have any lock washers on the bolts that I removed today on my '60. Maybe that was an attempted fix in later models or did my engine builder forget to install them?? Should they be there??

[Jim L.]

Re: water pump bolts

Keith, I've never taken apart an SBC that didn't have split washers under the heads of the water pump bolts. I think your builder forgot them.

Jim

[Joe L.]

Re: water pump bolts

Keith, I've never taken apart an SBC that didn't have split washers under the heads of the water pump bolts. I think you builder forgot them.

Jim

Jim-------


I don't know about C1, but C3 did not have lockwashers under the waterpump bolts. I don't think C2 did, either.

[Jim L.]

Re: water pump bolts

Jim-------


I don't know about C1, but C3 did not have lockwashers under the waterpump bolts. I don't think C2 did, either.

Joe,

I don't know squat about C3s but you've got my curiosity up regarding C2s. I'll take a look at my '63 today and report back.

Jim

[Keith R.]

Re: water pump bolts

Thank you Jim and Joe. You were right Jim - the Service Guide says nothing about split washers regarding the R&R of the water pump however the AIM page L104 shows a lock washer on the generator support arm stud and the TIMJ says on page 235 that there are lock washers at all four mounting points.

[Joe L.]

Re: water pump bolts

Thank you Jim and Joe. You were right Jim - the Service Guide says nothing about split washers regarding the R&R of the water pump however the AIM page L104 shows a lock washer on the generator support arm stud and the TIMJ says on page 235 that there are lock washers at all four mounting points.

Keith-------


A lockwasher is used when there is a bracket or brace that attaches to a waterpump stud or bolt. The lockwasher is installed on the outer side of the stud or bolt and against the bracket or brace. Otherwise, there are no lockwashers on waterpump bolts at least for C3 and, I believe, also C2. I'm not sure about C1

[Jim L.]

Re: water pump bolts

I surveyed my original-engine cars this morning. All of them have lock washers under the water pump bolt heads. The vehicles are:

'63 w/300 HP engine
'60 w/290 HP engine
'57 210 passenger w/220 HP engine

The attached picture is of my '63.

.101_8397.jpg

[Leif A.]

Re: water pump bolts

Yup...my original engine '67, as well.

[Keith R.]

Re: water pump bolts

Didn't mean to hijack the thread Carl but this is helpful to me as well as I am getting ready to put the water pump back on.

Jim, so it looks like C1s and C2s all have the lock washers but I am wondering if there is one under the stud on the upper passenger side where the generator support arm mounts? Specifically, between the stud and the block?