1991 Overheating after 383 build
#21
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
#22
Team Owner
Pro Mechanic
That test is pretty conclusive. I'd be "getting after" the water flow issue, IIWM. I'd have the pump off, checking the impeller.
#24
Pro
Thread Starter
Hose clamp? Definitely no problems there.
#26
Team Owner
It's beginning to sound like incorrect head gaskets and the fix will probably mean taking the heads off and installing the correct gaskets.
#27
Team Owner
Pro Mechanic
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.
Water pump may be new, but that is not a guarantee (to me) that it's good, because....China.
#28
Pro
Thread Starter
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.
#29
Melting Slicks
That^ is not right. That is old lore. You can't flow coolant "too fast" and cause overheating in modern cooling systems.
I find it odd that you posted that...then went on to say that you installed a t-stat that allows more flow. (?) Shouldn't that have caused it to run hotter, according to the first part of your post?
I find it odd that you posted that...then went on to say that you installed a t-stat that allows more flow. (?) Shouldn't that have caused it to run hotter, according to the first part of your post?
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.
#30
Team Owner
Pro Mechanic
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.
It became obvious that the coolant flow in my 406 was restricted. Why that odd or "wrong' to you is baffling.
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?
#32
Melting Slicks
I think it may be helpful if I shot a video of what happens. Everything points to exhaust gas getting into the coolant, via bad headgasket or cracked head, but the block check test kit shows up negative for hydrocarbons. Also, the lack of circulation issue is definitely a weird one. Could be a separate issue or related.
I'm just so bummed that after spending over $6000 I still can't drive it.
I've had this car for 11 years and will keep it forever. If I wasn't so attached to it, I would have gotten something else with that kind of money.
I'm just so bummed that after spending over $6000 I still can't drive it.
I've had this car for 11 years and will keep it forever. If I wasn't so attached to it, I would have gotten something else with that kind of money.
#33
Pro
Thread Starter
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!!
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.
#34
Pro
Thread Starter
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.
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.
#36
Melting Slicks
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.
#37
Le Mans Master
Member Since: Oct 2002
Location: Las Vegas - Just stop perpetuating myths please.
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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.
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.
#38
Pro
Thread Starter
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.
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.
#39
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.
Last edited by ex-x-fire; 09-07-2015 at 05:15 PM.
#40
Le Mans Master
Member Since: Oct 2002
Location: Las Vegas - Just stop perpetuating myths please.
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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.
Hang in there Bubba.