Ok, been dealing with this for a bit. It's a new to me car, but the issues are driving me crazy. I have been searching google for days. My issue is that I believe when I fill it with coolant, I get a huge air bubble. See pictures. My mechanic friend says no way. Ford design with 16psi will blow it into rad, which will also just require frequent topping up. Anyway you can agree or not with that statement, I still am getting fluid loss at rad cap area. On my second cap also.

The car was built at a professional shop that has done 9 in the 90's loosely based on martins kit. Not perfect but not like a new build nor a backyard hack job. All is from a 93 mustang and such. I live in Canada where ambient heat is not the issue with overheating. It burps fluid out the rad cap (it seems) after or during running for 10 mins. I have never seen it in action. Apart from crap, fluid on the ground, fluid missing, and telltale fluid stains from stopleek staining as well as fluid nearby filler.

Have replaced the cap
The thermostat
The fluids
The leaky coolant bypass hose

It has. The two following issues:
Unknown rad with filler on the top right

Kids came in, I am still finishing post...continued in an hour or so.

 

Post reserved for the second half of all the information. Sorry. Have re typed this post too many times. Life is busy, please wait.

Mods, can we set the login times longer than an hour or so? Having to relog on with a frustrating ipad is not fun. Posting with this poc is an exercise in patience.

Anyway, check out the photos. I tried buying the filler neck from Martin but he hasn't responded. Or jags that run have a neat viewer and relief valve. That will show if water pump works as well as air in system. I am not there yet as I am still thinking about using the throttle heater hose as a bit of a air bleed, however, that is pre thermostat, and I think my problem is post. See the photos why I think there is a huge air pocket. What do you think likely hood of air pocket vs head gasket as bob suggests? I will see if I can rent the tool.

The other issues are I don't know what type of rad I have in there to know if the rad cap is truly the issue or not. A mustang rad cap seems to fit pretty good but maybe that's the problem?

I will be trying to fill that goofy red adjustable rad hose, then attach it to the rad to eliminate as much potential air as possible.

I even bought at 91 ford crown Vic thermostat housing with the 45' output so it keeps the red hose a lot lower than the up hose setting. My guy assures me at 16psi and a good water pump there is no chance the hose makes a difference, just keep topping up the rad cap and overfill over three days.

Absolutely he thinks it could be head gasket as well, but we are hoping it is air first. Ok, just I am....




The other thing to try I guess is a vacuum filler as well.

Plus that goofy metal top hose won't allow for me to burp the top hose, nor buy this,

http://www.amazon.ca/gp/offer-listin...&condition=new

Or

http://www.jegs.com/p/JEGS-Performan...06366/10002/-1

 

My first thought is a blown head gasket. Go down to your local parts stroe that loans tools, and borrow/rent a coolant test kit. That will give you the answer in 30 minutes or so.

Alternatively, you can have the coolant tested for byproducts of combustion.

 

Here are the jags that run cool parts:

Stealth Conversions V8 Cooling System Parts - Coolant Sight Glass

Stealth Conversions, Radiator Hose Splicers & Custom Hoses, V8 Chevrolet TPI & TBI & V8 Swaps

 

My kit came with the Jegs type filler.

A vacuum filler works great.

Drilling a small hole in the thermostat (or using a Motorcraft thermostat) will help with filling the system.

Removing the ECT sensor & filling from there with an EGR coolant hose removed will help bleed air.

Do you have the correct radiator cap? Coolant should not leak at the cap, only out of the overflow when under pressure.

When running, does the coolant bubble in the overflow tank? (a sign of a blown head gasket)

Is the correct water pump on the car, & is it turning in the correct direction?

 

I bought one of these & I wish I had bought one years ago.

 

Doesn't look like you have any fluid in the overflow tank. If no fluid in tank, why isn't it getting there?. Hose from cap should run to the overflow tank that has fluid in it. When fluid in the engine expands to above 16 psi it is supposed to lift the spring in the cap & dump to the tank. When the coolant cools, the engine will suck the fluid out of the overflow tank & back into the engine. If no tank fluid, it will eventually run the engine low.

 

Looks like his overflow is in the usual spot for a 5.0, on drivers side shock tower.

 

Good eyes. I fill it half full now. You see second photo has white tape. I sharpied the spot and dated it, back when it had only minor problems. Optimistic of me. Thinking it had minor issues.

 

The odd thing is that (from the description) fluid is pushing out of the cap & onto the floor. It would normally push out through the vent on the overflow tank if too much fluid was coming out. Although, if exposed to the combustion chamber the high pressure spike could force it out through the cap & to the tank. Is the line to the tank restricted or plugged up anywhere? If not, what color is the oil? Chocolate milk & it's definitely a head gasket.

 

Can confirm T-stat is open &/or pump is working by feeling the lower radiator hose & radiator after it reaches operating temp, if it can be checked before it spits. If T-stat is open & pump is working, lower hose will be hot & you will be able to feel heat in the radiator, warmer low, cooler up top. Can check @ any time you feel the engine has reached a temp that would open the T-stat.

If no pump or T-stat is stuck, lower hose will not be hot, but cool or luke warm & radiator will feel cool.

Check heater core in cabin w/ heat on high. Check for leaks everywhere.

Maybe the T-stat or pump failed causing an overheat & a blown head gasket.

 

Three suggestions for a fellow Canuk -

1. Potential rad cap mismatch - you mention you don't know what kind of rad you have. Clearly isn't a Miata rad, nor a period Ford 5.0 HO rad. As a potential mismatched cap could be contributing to the problem, the rad model would obviously be good to ID. I recall from the ad for your car in this forum (I considered buying it last year!) that it's a Monster Miata (1 of 9, I think) build by Cardiac Cobra of West Vancouver so you might try Cardiac by email (info@cardiac-cobra.com), or John Brettoner (https://www.linkedin.com/pub/john-brettoner/44/a0b/752) who was the principle of Cardiac at the time or even Monster Miata to see if they remember what rad went with their kits at the time. This bit of sleuthing might get you the right cap for the mystery rad.

2. Eliminate the blown head gasket. Sure could be this, though it's a lesser possibility, so drain the oil into a clean container to check for chocolate milk colour or coolant separating from the oil. You also have a shop check it if in doubt. Then take a sample of coolant to a shop for testing, they'll confirm if you have oil contamination.

3. Air intake at the suction side of the water pump. My sense is that this is where your problem will lie. You can do an easy check by running the engine at a fast idle (once you've eliminated the head gasket issue, that is) while you submerge the end of the overflow tube in water. The radiator pressure cap should be on, but its lower pressurizing gasket should be made to leak by inserting a wooden toothpick or match between it and the gasket seat. If you see a steady stream of air bubbles from the tube, shut off the engine and confirm the clamps on the lower hose and heater hoses are tight. If you still have bubbling, check the water pump housing for a gasket leak and tighten the water pump bolts. If leaking still persists, I think you've nailed the culprit -- the cure will be replacement of the pump.

Hope this is useful, good luck!

 

I'm going to go with the above and suggest one more thing, could you have the wrong water pump? I have seen people install reverse rotation pumps by mistake (rebuilt and packaged wrong). Along with that is the issue of cavitation. If your pump is not spec'd for the car and has small fins it could be losing it's pumping effect. Had this happen t me on a Pontiac. Installed the Edlebrock hi-flow pump and cured.
I am really tending to think your issue is mostly in the cap. Having it puke out the cap and the burp bottle being empty says blockage to the burp hose/wrong cap. Don't forget the cap is supposed to let fluid flow out hot and back when cooling. If it is blocking the outlet hose (Too big a seal) it just ain't gonna work.
By the way, Mr Gasket makes a cap with a temp gauge built in so for under $30 you can see what temp all this is happening....