I recently did the rmw head install and everything went perfectly. But my coolant reservoir started to boil and actually leak. I was driving and smoke just blinded me and I had to pull over. Opened the hood and a cloud of smoke j slapped me in the face.



I didn’t know if it was the cap or not and I had an aluminum tank waiting to be installed so I just installed the aluminum one (ebay). I brought it to a shop and they installed the tank and fixed a couple other things like fuel injector leak and broken dash. They made me drive it after they finished but the temp was hot. They diagnosed It and they said it was a bad thermostat. I took it back and got one from mini dealer, changed it and drove it. Seemed fine at first but the temp went back up high. I tried bleeding the coolant but whenever I open the front bleeder screw when the car is on only smoke comes out even if I top off the coolant tank. I don’t understand. There seems to be a slight hissing and bubbling at the thermostat housing but no major leakage anywhere. Forgot to mention whenever the temp is hot, the little sideways nipple on the new coolant tank spits smoke. That’s why in the picture the coolant tank looks disgusting. I am lost. Maybe I forgot to connect something when doing the head idk any help is appreciated thanks!

 

Some possibilities:
>coolant system needs more burping - try elevating the front end or park on an incline to help it along. Remember to burp the lower bleed screw first (down low on water pipe running behind block) and then the upper bleed in the upper radiator hose connector
>thermostat housing gasket may be pinched and leaking
>(plastic) thermostat housing may be cracked and leaking
>thermostat is installed incorrectly; the small hole in the thermostat disc goes at the top (12 O'clock) to allow trapped air to escape the engine during bleeding
>low speed is out on fan resistor (very common)
>head gasket issue [edit: disregard previous comment on milk shake - that's an oil cooler thing]

 

Was your car running fine/not overheating prior to your replacing the cylinder head?

You said when you open the front bleeder screw with the engine running, only smoke comes out. You should leave the screw open until coolant starts to come out before you close it - that's how air in the cooling system is let out. So let it all out.

That makes me wonder also if there may be a restriction in the cooling system? Like an accidentally pinched hose or a misrouted hose/connection? I know in pulling the head there isn't much of the cooling system in the way to mess with but maybe you did other work along with the head?

Like @Daftlad mentioned, make sure your cooling fan comes on. Start the car with A/C on and the low speed fan should be on. When your car was overheating, do you remember hearing the high speed fan running?

When you fill your expansion tank, you only fill it about halfway correct? It should not be full to the top.

You installed a new thermostat, so we can check that off.

That leaves airflow through the radiator, coolant circulating in the cooling system (water pump), cooling system able to hold pressure without leaking, cap able to hold pressure...

If all that checks out, then maybe it would be time to test for combustion gases in the cooling system. Let's hope you don't get to that point right now though.

 

>bleeding

quick reminder of the need to run the heater at full blast / max temp ("HI" if the car has automatic climate control) while bleeding the system. There's a labyrinth of coolant pipes between the motor and the firewall two of which service the heater core. If that wasn't done, yet another place for air to hide out...

Pretty good overview of bleed procedure over on Pelican in their tech articles section:
https://www.pelicanparts.com/techart...ant_Change.htm

 

Is it possible you installed the head gasket upside down and blocked water passages?

 

I brought it to a shop and i am guessing the mechanic tested to see if there were exhaust vapors coming through my coolant system and what he said is that my head is cracked. I dont believe it and thats prob because I just dont want to admit that the rmw head is cracked but I genuinely think that my gasket was shot because when I received it, it was on a cardboard board but the side where the timing chain goes was really bent. I stuck it under my bed where its dead flat for about a month and when I removed it it was better but not 100%. There is only one way to find out. Since I am in school I will wait to take apart the head during Christmas break because I have so much work to do especially apply for college and stuff. Wish me luck

To what cooper48 said, isnt there only way the gasket would fit? I tried flipping the gasket and seeing if it fits but theres a little dial that makes it only fit one way. So I am sure i fit the gasket the correct way.

 

Sounds like it needs the coolant bled better..jack the car up, open coolant reservoir and fill it and then fill it through that bleeder screw until it also topped off. Then close bleeder screw and with coolant cap still off squeeze your coolant hoses a few times as hard as you can to force fluid around.
then start it and once it reaches your thermostats opening temp , then remove the bleeder screw again and it SHOULD start spraying out the second its renoved enough so go slow. If it doesnt spray then while it's running , begin filling through that bleeder screw hole again. The skinny funnels will butt up against it enough to not leak out if you fill it slowly. The 1$ stores funnel is actually perfect for it.
have you verified your waterpump is turning ? I wonder if your sc gear on that end may have gone bad or the waterpumps.

 

What evidence did the mechanic provide that the head is cracked? I would expect if a mechanic were to make that assertion, he would be able to show and/or explain what evidence he discovered and how he came to that conclusion.

You did not say whether or not your car was running OK prior to replacing the cylinder head.

 

I asked him, what made you say that it was cracked? He goes “my friend because we are experts” so I know the guy was “BSing” the whole thing. I think it’s just a head gasket leak.

the car was running perfectly before. No coolant issues at all! There was a slight oil leak but that was from my oil filter housing gasket to which I replaced when I did the head. But everything else was perfect!

 

Wow. What an amateur response from one who presents himself an expert.

Was it a brand new head you installed? Did you thoroughly inspect it yourself prior to installation? I don't suppose you checked it for flatness with a precision straight edge prior to installation?

I don't think I would have installed that bent head gasket. I don't know how bent it was, but perhaps enough to prevent a good seal. Was there a crease in it?

 

very annoying mechanic I know. It was the rmw head that I installed meaning brand spanking new. 0 miles. The gasket wasnt creased that I know of I honestly forgot how bent it was. I did not check the head for flatness but the thing is is that they resurface the head and check for any cracks of that kind.

 

Back to basics. We will assume your head and gasket are not the problem for now.

I was just rereading your first post and looking at the pictures. What is that chocolate milkshake looking ooze on the expansion tank in the first picture? I know Mini coolant is blue and when my cap was allowing coolant to leak out of my expansion tank, it looked like blue coolant, not that ooze in your picture.

What does the coolant look like in your expansion tank look like right now? I'll assume you filled your cooling system with new coolant mixed 50/50 with water, so it should still look like clean coolant.

What is the coolant level in the expansion tank with a cold engine? A full cooling system should show coolant to maybe half of the expansion tank.

@Daftlad gave a good list of items to suspect for overheating. Have you looked into those suggestions?

Do you have access to a cooling system pressure tester? For the original expansion tank, there is an adapter to screw on the tank to accept a pressure tester. Does that aluminum expansion tank have a unique cap or is it similar to the OEM cap/threads. I don't know what the cap blow off pressure is for sure, but I pressurize my cooling system to about 110 kPa (about 15 psi) when testing it. A properly sealed cooling system should hold maximum pressure indefinitely but I am usually satisfied if it holds for a minimum of about 10 minutes. If it drops a couple of psi or so with no external leaks and then holds, that is a sealed system in my experience. If it continues to lose pressure, that is a problem.

There are adapters to test expansion tank caps (and radiator caps for those systems) with a cooling system pressure tester. If that aluminum tank has a unique cap, it may be a problem to verify that cap will hold pressure. If it is OEM style, I have the adapters. Mine are Snap On brand but I could provide the part numbers for cross reference to match up with reasonably priced brands so you can test the cap and cooling system.

Once you have verified you have good coolant, filled to the proper level in a sealed system with a cap that will hold pressure, it's pretty much down to:

- airflow through the radiator
- radiator fan not working
- restrictions (pinched hose, incorrectly installed thermostat, incorrectly routed hoses) in the cooling system
- water pump circulating the coolant
- cylinder head/head gasket problem

I know this can be frustrating. I replaced my engine earlier this year after overheating my original engine and warping the head. My newly installed engine was overheating from the start after I repaired what caused my original engine to overheat (a broken coolant tee). I had all new coolant hoses and tees, new radiator, all new seals in the engine, new oil cooler and 1 year old water pump. My cap was 4 months old and my thermostat was 1 year old. By following the steps I and others listed, I found that my expansion tank cap wasn't holding pressure. Replaced it and still overheated. Replaced the thermostat and that was the final piece to the puzzle. My cooling system has been perfect through the summer in here in Phoenix, AZ.

You will get through this.

 

I was wondering that myself. Have you by chance checked the oil?

 

So I used some head gasket sealer for the mini. It worked the car doesn’t over heat anymore, but my oil became chocolate milk. So it didn’t fix the problem but at the same time it did. No idea what happened there. I’ve been getting a lot of feedback saying I shouldn’t have done that especially from my dad but idk it worked my car doesn’t over heat anymore. Now I assume that none of my coolant passages are blocked since my car stays cool? Which is a good thing but let me know what you guys think

 

it was the head gasket. Check my recent reply

 

If it were me? - R&R the head and replaced the potential bent head gasket. Scrape and clean that sealant off your new head. Replace the head gasket with a good, new one. Drain the coolant. It should kinda go without saying but: I would also without question - drain and do an oil & filter change.
I would defer to the more seasoned wrenchers here with respect to any insight on an engine flush.

I have to admit I've made some mistakes when I built my first few (non Mini) engines decades ago. What I've learned from my mistakes; is not to be complacent by putting a "band-aid" fix on things that are important. I think you would agree that this one is important.
Pay the price and learn from your experience. Do it right.
Heck, I'd really like to continue hearing you around the NAM forums knowing that a young guy was not afraid to twist his own wrench and has a pretty cool Mini as a result.

Good luck.

 

I certainly hope that you've changed both the oil and oil filter after seeing "chocolate milk" in your oil pan. A coolant flush/change should also be on your to-do list.

 

I'm glad you've got it diagnosed. That's really good news!

I agree with @Here2Go and @cooper48.

In my opinion, anything other than a full, complete repair is a merely a temporary repair. The head gasket sealer worked in that it helped with diagnosis, but you spent good money and your own labor to put a high performance cylinder head on your car. Your efforts deserve the outcome you envisioned when you ordered that RMW head.

 

thanks a lot. I decided I will wait until I finish applying to all the colleges I have in mind to do the head gasket one more time.

but really quick, what are my possibilities when I remove the head? What I mean is what could I potentially find when I remove the head?
cracks, broken valves, etc?

 

I will. Don’t worry. All fluids will be changed at one point

 

100% agree with you. This cylinder head replacement was the worst financial decision on
my end! My father only helped me on it because he wanted me to learn how to work on engines. This is all a learning experience for me and the fact that I didn’t even know how to change my oil before I removed my head! I appreciate NAM very much. And Mod Mini too!

 

R&R Head =
College!!! =
I have to admit - I've never dealt or R&R'd a head on a Mini.
If I understand correctly, the head you installed was brand new (?). If this is the case; I guess I would then ask how long did you run the car and under what conditions before you discovered the over heating issues?
Hopefully not too long or a spirited romp around the neighborhood. If you weren't too rough on it after the rebuild and the head components were new (valves,seats springs etc...), I think it "might" be unlikely to have burned or bent a valve.
Regardless, I would do a very thorough clean up and a keen close inspection for any cracks or hairline fractures. In particular I would have or check the plane/ flatness of the head / gasket mating surface. The overheating issues could cause the head to warp.
I'm not sure about the bolts (re-use or replace), but check and make sure the threads haven't started to strip.

Again, I am not a seasoned Mini mechanic. So I respectfully defer to the more knowledgeable here on NAM to offer further insight / advice.

Good luck with getting the Mini sorted out and hope you are accepted into the college of your choice!

 

the head I sent to Jan was my old head. 184k miles on it. Now that I think about it it’s possible the head is cracked. But I must say this. When I received the head, the job was horrible! The spark plug tube was dented so I couldn’t install my plugs! Cam caps were also dented so I had to do light sanding to make it sit properly. Last but not least the cam journals had the smallest lip making the camshaft not sit fully. I lightly sanded with 2000 grit and indeed the cam seated properly. Messaged Jan about the cam and the cam caps and he said he didn’t play with them. Idk how that happened but I know for a fact the machine shop he sent the head to didn’t do an after inspection on the head. That being said I can say that it’s possible the bottom surface of the head wasn’t done well.

When I started the mini for the first time my gauges weren’t working. And ofc since it was basically a cold start I didn’t know there was a head gasket leak. So I waited for a while waiting to get the car warmed up and to give it a couple pulls and it was very fast even without the cam. But than whenever I would come to a stop I see smoke seep through the gaps from the hood. At that time I thought it was just fluid that I spilt landing on the exhaust so I didn’t think much of it. I got the gauge fixed at a shop and than that’s when I knew the car was overheating. So as painful as it sounds I was driving the car for a little with the overheating issue. I pray everyday that there isn’t a crack on the head or as you said a bent valve. I appreciate all ur help. Worst case scenario, if the rmw head is cracked or warpedI have a stock head that is perfect only a spark tube is loose so I need to replace the gasket and I don’t know how to do that but it’s doable so I would install that one with the rmw cam. So I should be getting some good power but not as much with the rmw head.

 

Just wanted to ask one other question since this popped up in my head recently. When replacing the head I didn’t engage my chain tensioner causing my engine to come off in timing. Since then I’ve been cranking the car trying to diagnose what went wrong and after about 3-4 days of diagnosing I finally figured that it was the timing. Now I’m wondering is it possible that the offtiming of the engine caused excessive pressure to the point that it caused a head gasket leak? And especially since I didn’t have my gauges working I thought it was working perfectly fine so I pushed it a little which made the head gasket leak worse. Is that all possible?
thanks

 

If your engine was out of time, you would have LESS compression than an engine properly timed.