coolant leak very strange

[Ronald D.]

Re: coolant leak very strange

Mike, no leaks from the intake gasket, when the manifold was removed there is water still in the head dripping out the first exhaust port, none of the intake bolts enter water jackets, there either in solid material, or enter the valley area where oil is, I will know the whole story on Monday or Tuesday after the machine shop does the testing, Ron

[Ronald D.]

Re: coolant leak very strange

Here is the update on what happened with the leak, they pressure tested both heads, the one that was leaking was found to have small cracks and and a small hole under the first and last exhaust seat on the right head, they removed the two seats and that is where the leaks came from, the machine shop said they feel there was some rust at some point in the head, then when they machined the head for new seats and pressed in the seats it caused a crack, they tested them before the work and were fine, now they will retest all the heads when done. These heads were surfaced, new valves, and seats, guides, studs, springs everything was replaced but the cast head, there in the process of finding a replacement head with correct casting and dates, it sure was easier to work on when the body was off

[Michael W.]

Re: coolant leak very strange

Not to add insult to injury, but there was no probably need to install new seats in the first place.

[Joe L.]

Re: coolant leak very strange

Here is the update on what happened with the leak, they pressure tested both heads, the one that was leaking was found to have small cracks and and a small hole under the first and last exhaust seat on the right head, they removed the two seats and that is where the leaks came from, the machine shop said they feel there was some rust at some point in the head, then when they machined the head for new seats and pressed in the seats it caused a crack, they tested them before the work and were fine, now they will retest all the heads when done. These heads were surfaced, new valves, and seats, guides, studs, springs everything was replaced but the cast head, there in the process of finding a replacement head with correct casting and dates, it sure was easier to work on when the body was off

Ronald-------


This is EXACTLY the reason that I usually advise against the installation of hardened valve seats and especially for heads with 2.02"/1.60" valves. One can usually get away with it for 1.94"/1.50" and smaller valves but for the larger valve size, it's a HUGE risk.

[Jeff P.]

Re: coolant leak very strange

Joe.... Does the gasoline from todays refinery really possess problems to the exhaust seats? I always use hi-grade Sunoco. Someone rebuilt Ronalds heads to the fullest minus the porting job needed to make horsepower, and ruined them. Dont change them seats men unless the valves are sinking into the heads from excessive grinding on the seats from Bubba. Know your local butchers before they touch your original parts.

[Joe L.]

Re: coolant leak very strange

Joe.... Does the gasoline from todays refinery really possess problems to the exhaust seats? I always use hi-grade Sunoco. Someone rebuilt Ronalds heads to the fullest minus the porting job needed to make horsepower, and ruined them. Dont change them seats men unless the valves are sinking into the heads from excessive grinding on the seats from Bubba. Know your local butchers before they touch your original parts.

Jeff------


I don't think that today's fuel poses any significant problem for valve seats in older Corvettes. If one is still nervous about it, simply use a lead substitute containing PowerShield. The concentrated products containing it only require the addition of a few ounces to each tankful.

[Ronald D.]

Re: coolant leak very strange

I think this got a little track, if you read the complete post everyone will see these heads were completely rebuilt with hardened valve seats, one head now passed a 50 pound pressure test the other one did not, there were some who wanted to know the final outcome of where the leak came from

[Michael W.]

Re: coolant leak very strange

Joe.... Does the gasoline from todays refinery really possess problems to the exhaust seats?

The 30+ year old myth is that lead is required in the fuel to stop the valve seats from eroding. Many of us accepted it at face value back in the day but experience gained in those 30 intervening years demonstrates that such damage will only occur on engines that are under heavy load for extended periods- motorhomes, racing boats, heavy trucks, etc.

Lightweight Corvettes ripping through the gears in a 1/4 mile or cruising on the highway just doesn't create the right conditions long enough or hard enough to induce wear. As seen here, converting the heads to hardened seats is not always a benign process.

[Joe L.]

Re: coolant leak very strange

I think this got a little track, if you read the complete post everyone will see these heads were completely rebuilt with hardened valve seats, one head now passed a 50 pound pressure test the other one did not, there were some who wanted to know the final outcome of where the leak came from

Roger------


Yes, we're very glad that you reported the outcome. Everyone should do that when they've reported a problem here and asked for advice or further information. It's what can be called "closing the loop" and it's very important and part of the learning process for everyone.

In this case, if you had asked the question (or reviewed the archives) regarding the installation of hardened valve seats prior to having the heads rebuilt, you might have saved yourself a lot of trouble. In any event, we offered advice in this thread on the hardened valve seat issue using your experience as an "object lesson" in order to caution other folks.

[James G.]

Re: coolant leak very strange

Not to be a smart ass, but engines I had rebuilt I have had the engine rebuilder test it on his DYNO once rebuilt. Cost an addition $300-500, but once complete and broken in, I can install in the car and I know I won't have to re-do.

[Ronald D.]

Re: coolant leak very strange

Hind site as they say is 20-20, but the machine shop I used doesn't have a dyno, they are fixing the problem, but having a hard time locating a replacement head, the head is a #3973487, there were a two versions used back then, the LT-1 had the large valves, and screw in rocker arm studs, the 270hp engine I guess also used that same casting number but had press in rocker studs and smaller valves, the low HP heads are out there but the LT-1 big valve heads are not real plentiful so I am trying to find a decent one, anyone has any leads let me know, thanks Ron

[Patrick H.]

Re: coolant leak very strange

You can check out Engines Limited in Wisconsin as well as other Driveline advertisers. I purchased a date matching head from them several years ago.

In addition, any 270 horse head can easily be converted to the LT-1 configuration. If your machine shop doesn't know how to do this well then....

[Joe L.]

Re: coolant leak very strange

You can check out Engines Limited in Wisconsin as well as other Driveline advertisers. I purchased a date matching head from them several years ago.

In addition, any 270 horse head can easily be converted to the LT-1 configuration. If your machine shop doesn't know how to do this well then....

Patrick and Ron------



Yup. A standard 3973487 can be converted to SHP very easily. At one time, Flint used that same casting to machine either the standard head or the LT-1 head. So, if they could do it then, a machine shop can do the same thing now. All that needs to be done is enlarge the valve openings, remove the pressed-in studs, machine the bosses for screw-in studs, install guide plates and screw-in studs, and install new valves. A side benefit of this is you end up with a head with as-new valve positions in the heads. So, even if the core you use had several previous valve jobs with resultant recession of the valve seats (and consequent increase in combustion chamber size), the head is returned to as-new with the larger valve installation.

By the way, once a head is converted, no one could tell the difference between a converted head and an original head. No one.

[Jeff P.]

Re: coolant leak very strange

Ronald check on Ebay they're many sets and possibly with the correct date code. Good Luck!

[Ronald D.]

Re: coolant leak very strange

I asked the question about the two heads, now that I know there the same except the machine work I won't have a problem finding one with a decent date code, I have not talked to my machine shop, but offered to spend some time looking, they are doing the same, and yes they would have no problem converting one to LT-1 specs, thanks for all the info, I want to get past this and move on to finishing the car, windshield, top dash pad and roof stainless is what I am now working on, 6 more months it may be on the road