Hey!

After my inframe renovation of my 1990 renix I am finally starting her up again!

now the smoking is pretty massive and I don’t know if it’s just normal oil burning from all the messing around, an exhaust leak or if it’s about to blow up.

smells a bit like burnt rubber, no gas leaks what I can see

what does it look like to you?
please give me some expert advice, I have zero experience here

 

Well the vid was a bit too short to tell. It looked like oil burning off the exhaust. How much smoke came out of the tailpipe?

Wipe any visible oil off the exh pipe, bell housing, oil pan and trans pan. If it runs OK, let it run for 10 minutes or so (let it get up to full temp). Keep checking oil pressure. If all good, go for a short drive. Check for any oil on the floor before you go.

 

Oil on the exhaust will make a surprising amount of smoke. As long as its not coming out of the tailpipe and the engine isnt making any weird noise you should be fine.
Sounded ok in the video and just looked like oil on the exhaust.

 

Hi again

so today I cleaned up the exhaust real good, checked all fluids again and fired up.

at first everything is jolly good apart from the engine vibrating on an interval-I assume that’s a misfire?

next-after idling for around 10 mins the smoke is gone, I get up to temp, I blast the air con to check the Aux fan but it didn’t want to come on. I know it works so something else. The engine is almost stalling but picks itself up just in time. I figure it is learning the idle.

but then I look over at the pressure bottle-WHAT THE ****?!

renix pressure bottle totally boiling over, i rush to shut the engine off with a fountain of steam and boiling coolant from the cap as a result. Great

I attach a video from just before this happens, to hear what the engine sounds like

what the hell just happened, and where do I go from here?

 

I assume the gauge reads Celsius. The caps on those bottles are known problems. Once they leak, the pressure releases and the coolant boils over. If you try to tighten the cap, it feels like it's stripped.

So a few ways to workaround/fix it.

1. Snug (not too tight) a hose clamp on the cap. Tighten down the cap. The clamp prevents the sides of the cap from expanding and slipping off the threads. Once the cap is tight enough, tighten the clamp a bit more. This will keep the "threads" on the cap tight to the bottle. I ran my '88 like this for a short while until I did the next one.

2. Get a Volvo bottle cap. Don't recall which model, perhaps the pic will help or someone else will chime in. This is what I use now. Had several similar "boil overs" with the old cap. Did the hose clamp for a while, then switched to the Volvo cap with a new bottle. Have had this for about 10 years now. Nice tight fit, no leaks here. Keeping my cooling system maintained keeps my max temps below 220F (and that's on a hot SoCal day).

3. Convert to open system. You'll likely get this response from many folks that have done it. Lot's of YT vids and posts about this solution.

4. Some may suggest an all metal expansion tank. This should work but the tanks and parts to use it, can be almost as pricey as the open system swap.

Volvo cap on expansion tank.

 

Ok thanks for these tips!
A few notes/questions;

Radiator cap was brand new so should be fine I guess, will look into your clamp trick!

-Radiator has a slow leak, dripping from a bottom corner- would this affect holding pressure in the system?
-I filled the bottle up to the highest point of the post, is this overfilling?
-Can trapped air be causing it to boil over? I burped the system through the temp sensor hole with the back raised up, but hard to tell if I succeeded

Since I lost a lot of coolant, I assume I now have air in the system- do I need to get the temp sensor out again or what do you recommend?

many questions, haven’t gotten my head around how this system works even after watching many videos….

 

In my own experience, once the cap is compromised, it will continue to slip. However, give the hose clamp a try.

Yes, any leak, no matter how small will bleed pressure and eventually result in over heating.

If you mean the post you see inside the opening, no, but that is the high mark. Do not fill more than that. The tank is not an overflow, it's an EXPANSION tank. So it needs the air space to allow the coolant to expand and not rupture the system (typically making the cap leak). The notch on the post is "add" level.

It can depending on how big a bubble. The trapped air prevents coolant from making contact and drawing away the heat. I don't take out the temp sensor (too afraid it will snap off). Instead I run mine through a few heat/cool cycles using some short drives. Heat everything up to temp with heater on. Let cool, top off tank. Repeat until cold level returns to previous cycle (more or less). Admittedly, this could take a day or two. Some folks also drill a small hole in the thermostat oriented at 12:00 to allow coolant (and air) to pass while the thermostat is still closed (some thermostats even come with one predriled). When I replaced my radiator and hoses, I clipped the elbow part off the upper hose and used it like a funnel to prefill my radiator.

Some other methods above but use what you feel comfortable doing. You may not get all the air out right away. It will eventually work it's way out. Just watch your temps and check the tank level until it remains consistent.

 

Ok got it, thanks alot for your help.

A few more questionmarks though:
-I got a/c heat and cold+ both upper and lower hoses where warm (very), I assume that means that thermostat is ok, water pump ok and heater core not blocked?
-I’ve read some mentioning running the idle with the cap off until warm to get any air out, thoughts on that?
-is there any way to find out where the pressure is leaking out causing the system to boil over, other than looking for coolant leaks?

again, thanks for your kind help, much appreciated

 

If the upper hose is hot, like barely able hold it, the thermostat is open. I use an IR thermometer to verify temps at the t-stat housing and upper hose at the radiator. If the heater hoses are also hot, the heater valve is open (if you still have it) and coolant is flowing through the core. Again, outlet temps tell you how well it's flowing. At full temp with heater to full hot, mine will blow around 120-130F (so around 50C)

You can leave the cap off during the initial warmup. A 50/50 mix of water and glycol antifreeze won't boil until around 223–226°F (106–108°C) depending on altitude. That's well above the t-stat opening. If the coolant level begins to drop, just add a bit more. Just watch the temp. Once you get close to 223F/106C, I'd cap it off.

You can pressure test the system without the engine running. There are kits available that come with a handpump and adapter for the tank. You pump the system to about 1 bar (~14psi) and wait to see if the pressure falls. Some leaks can be hard to find with the fans, grill, and other structure in the way. If the core is leaking, you may see coolant drip of the condensation drain on the heater box, and smell coolant in the cabin. Mine had a very small leak for quite a while. No coolant on the ground but I could smell it. Very little loss in the tank so I just top off. When I finally overhauled my coolant system (new pump, rad, hoses fan clutch etc.), I found this. It was in the corner, behind the fan shroud. There was another spot on the ac condenser side.

 

ok thanks again for advice!

ahhh I see where this is going. That would be the look of my radiator right now. From what I understand upgrading (?) to open system is quite straight forward? Did you do that? Preferred? Buying a new pressure bottle and rad for the closed system is about the same money I guess.

After the jeep has been sitting for a few days there is around 3-4 dl of coolant in my drip bucket underneath the rad. So then I have to refill, and I guess that means possibly also introducing new air. This won’t last very long arrgh

When I got the jeep it had no coolant in the bottle and later turned out to have a destroyed piston, I guess from overheating. But then it was leaking from everywhere- t-stat housing, freeze plugs etc. That has been fixed. I guess a new rad is on my wishlist…

 

So after some more thorough investigation today this is what I have:

-radiator leaking, drips only after shutting down tho
-looks like my heater core is leaking too? I removed the floor mat and discover a wet trail from that factory gooey junk. What is behind here? Why this goo? Heater core is further up behind the dash no?

after tightening all clamps and hoses the jeep idled great for around 10 mins, never going over the 12 o clock mark on the temp gauge. And the e fan is not working. I guess it’s cooling somehow despite the small leaks?

What’s my next move?

 

A leaking radiator isnt going to cause overheating as long as it is kept full, and a depressurized system will not cause overheating by itself either. The reason for the pressure is to increase the boiling point of the coolant.
Most likely you just had an air bubble, combined with having the cap on, the air didnt really have anywhere to go. Usually first start on an empty system burps out a bunch of air and forces out some coolant.

 

ok, that sound a bit more comforting, although the rad really looks like it needs to be junked I guess.
But if I can have some time actually driving the jeep I might be able to muster up that energy .

I am a bit puzzled about my passenger side firewall leak (see pic in previous post) - from what I understand the heater core is more around thw centre console and this is the factory sealed up opening for…what?

 

Heater core is on the passenger side right where the hoses go through the firewall. Could be water leaking in from the cowl too.
Yeah that radiator looks like crap. Might be time to get a new 91+ radiator and some 97+ heater hoses so you can delete the HCV and expansion tank.