GALT4

Shot n the dark but they may not have connected the coupler when replacing the water pump. Not sure if thats the correct term for it or not but woildnt be the forst time ots been left disconnected

Tom400CFI

That test is pretty conclusive. I'd be "getting after" the water flow issue, IIWM. I'd have the pump off, checking the impeller.

Hot Rod Roy

I'm betting this is the answer! Have you tried ex-x-fire's suggestion???

Bubba91

Tried, but couldn't really tell one way or the other.
I had an Edlebrock High flo pump on there before the rebuild, which was only about 3 years old, but put a new one on just to rule that out last week; along with a new radiator, thermostat, and upper surge tank.
Hose clamp? Definitely no problems there.

GALT4

Not a hose clamp. If it's an LT engine, not sure on L98, there is a coupler that connects water pump to the drive off the engine. No coupler no water flow.

c4cruiser

Looks like the engine is an L98 so the W/P is driven by the serp belt. Only the LT1 and LT4 motors use a coupler to drive the water pump.

It's beginning to sound like incorrect head gaskets and the fix will probably mean taking the heads off and installing the correct gaskets.

Tom400CFI

Maybe. I know that *I* would be checking the pump and gaskets long before pulling heads. Those items are far easier to check.

Water pump may be new, but that is not a guarantee (to me) that it's good, because....China.

Bubba91

You make a good point,. However there is coolant flow when I take off the surge tank cap (that little stream that comes out, at the top) with my old and the new water pumps. I just think there is something getting restricted inside the engine.

whalepirot

This is exactly what I was told by the cooling engineers at a well-reputed water pump manufacturer. They suggested various-sized washers to find optimum water flow. The simpler and effective solution was losing the Stant and going with the Shaw.

It became obvious that the coolant flow in my 406 was restricted. Why that odd or "wrong' to you is baffling. I have no problem with being wrong and learning from those who have actually solved a problem I face. IN this case, I'll go with the cooling experts despite the decades of fleet mx so oft touted, thanks, as IT WORKED!

Too many think that more-is-better, like a high flow WP will solve a cooling problem, or an aftermarket fan will. I believe I wasted a lot of $$ throwing expensive aftermarket parts at a simple problem,when the stock Z51 components would have worked fine, had I know about the thermostat, which, BTW,also solved the same issue for pal with a near identical setup.

Tom400CFI

Maybe I'm confused. I thought that you said originally, that coolant could flow too fast and cause over heating....but then you said you switched to a higher flowing stat, and solved a cooling problem. By flowing the coolant fast, it would seem.

I definitely agree, that a better, higher flowing stat could help. I don't agree that flowing coolant "too fast" will cause over heating -it won't. I definitely agree, that increasing coolant speed (or fan speed) has diminishing returns; doubling coolant speed won't double cooling system performance, from a stock GPM rate.

So it seems more like I misunderstood your original post, perhaps?

THE 383 admiral

Are you sure the timing is correct? What heads were used????

desertmike1

Your right, this kind of flies in the face of conventional wisdom.. but, was the test conclusive, i.e. a good test kit, or done correctly? or maybe you truly have an isolated hot spot do to poor circulation because of a gasket problem.. I would hate to see you pull Heads for no reason!!

Bubba91

I'm going to do the test again tomorrow and also try a few of the things suggested in earlier posts. I will shoot a video of my problems.
I really don't want to pull the heads either, but I will if I have to. Most likely, I will buy a new set of Edlebrock heads if it comes to that. At least I will know that it was put back together right, this time.
I want to thank everyone here for their help. Hopefully, in the future, this thread will help someone else out.

Bubba91

So, I re-ran the block test kit and it came back positive for combustion gas in the coolant. I guess I'll either have to go back to the engine builder, who I do not trust, but accepted my $6000, or buy new heads and do it myself.
He fixed a couple of cracks, in the head, ported, and resurfaced them. All of this, I witnessed. I'm not sure if he magnafluxed or tested them, which worries me.
What else could be wrong?
Cracked block?
Could the heads be fine and maybe he used the wrong gaskets or poor assembly?
I just don't want to waste money on a new set of heads, if I don't have to.

ex-x-fire

I'd take it apart & take pictures, are the heads iron?

desertmike1

OK, it looks like you have a problem with an internal high pressure leak, this could be many things, but most likely associated with the top end.. i.e. Improper head bolt torque/Sequence, warped mating surface, cracks etc. I've never seen a cracked Block but I suppose it's possible, the block Head mating surface could also be Warped.

cardo0

Yea if u have combustion gas in the coolant its a serious problem. Head crack or gasket. Block cyl could have a tiny crack also. Im wondering if a leakdown test at both top and bottom dead center could locate the affected cyl(s). I really dont know how a leak down at BDC would work as have never done that but i have done the leak down test at TDC and u could try that first which maybe all u need.

I was going to suggest a flex shaft digital camera but if u have combustion gas in coolant i think that would be wasting time and money now.

Let us know what u find. It helps us all.

Bubba91

Well, I broke down and contacted the engine buider and took it back over there , for him to fix it. I hope it doesn't take another 2 months. He said he would figure it out, at no charge to me. He was still very defensive about there being an issue with the engine itself. However, after I told him everything I tried and that all signs pointed toward there being exhuast gas in the coolant; he said, he would take the engine out and run it on a stand if he had to, to prove it. I just said ok.
I would probably end up spending another $1500 and have to do all of the work myself, in the driveway, in the Florida sun and between rain storms. Working 50-55 hours a week, this didn't sound appealing, especially after already spending over $6500.
Hopefully, I can get my daily driver back and stop bumming rides to and from work Monday thru Friday, as it is 30 miles, one way. It really sucks, because I own my vette, a truck with a bad transmission, and a motorcycle that I do not care to ride everyday through nearly daily rain and 30 miles, each way, to work. Three vehicles and no way to get back and forth to work. At least, I have an understanding girlfriend and mother that have been giving me rides for the last three months.
Sorry for the rant and I will give an update, when I find out.

ex-x-fire

1st rule is always have a dependable daily driver before starting a big project. I would have taken it apart myself. Hope everything works out.

cardo0

Good to read the builder is cooperating now. I can read u love your vette but as ex-x mentions u are stretching your transportation kinda thin. Plenty of divorce have happened over old cars. Wouldnt like to read your life gets worse over this. FWIW u can buy cheap econo cars brand new for under $15k.

Hang in there Bubba.