Coolant flushes & leak stops

B0bbyEwing

Had a pretty decent idea on how to do a coolant flush, which I need to do on my car but chose to watch a Chris Fix YouTube video beforehand to just check & refresh myself.

I was pretty much right except at the end of the video the guy puts in some anti rust solution. I Googled it & since I'm going to be using Wynns rad flush I saw they also did a 'stop leak' 

Since the rad flush is in there for a short time yet this is in there as a permanent fixture, any of you have experience and opinions on this stuff?

Spoke with someone & they said they'd stay away from it unless I was getting rid of the car. They started talking about radweld & how it can cause issues, thin water lines etc & their assumption was it probably works like radweld & therefore can also cause issues too. 

Car is 12-13yrs old, 120k mile, coolant looks pretty grim - hence looking to do a flush.

Plus it's debateable as to whether it may be the head gasket going or oil cooler & not the radiator at all. Fingers crossed it's just the rad & old coolant.

Grey_Critic

Back many years ago they used to suggest the White of an egg. Problem with flushing is it can expose micro-leaks that were blocked by the sediment. There was also the problem of adding anti freeze - Drain a couple of pints and top up with AF. 

Oh the joys of motoring back in the old days. Used to have to stop to tune up rge twin SU carbs. Bit like a plane - Service repairs on a time basis. One hours drive you needed One hour service - Cross ply tyres, NO power steering - fun when trying to get in and out parking spots.

Mildly_Miffed

Don't put bodgegoop in unless the car's being nursed through its last year before scrapping...

facade

Exactly as Grey_Critic says, using rad flush often creates leaks by removing the rust & crud that was blocking them up!

Last time I tried it was in The Olden Days when radiators were made out of thick chunks of brass & solder, rather than aluminium foil, glue & plastic like today. Invariably the radiator would weep coolant afterwards for weeks.

The main thing was to bypass the heater while the radflush was in, a leak in the heater matrix involves stripping the car down like those photos you used to see on the back cover of a Haynes manual with all the parts laid out.

If you had one of those Quality cars like a Jaguar, you were supposed to put Barrs Leak in the coolant when you changed it, as Olden Days sand cast engine blocks weren't particularly watertight.

Up to you what you do, with a 15 year old car I'd be inclined to dump the water, get the hosepipe to it and flush it out, then fill up with water, run until hot, let it cool a bit and dump the water, flush again with the hosepipe, then add concentrated antifreeze and top up with distilled water if you have it.

There will still be lots of plain tap water in the system though, you can't drain them like in The Olden Days.

I'd only use a flushing agent if I was sure there was a blockage somewhere, and leak fixer if I had a leak.

You don't need to add a corrosion inhibitor as that is contained in the antifreeze.

B0bbyEwing

facade said:

Exactly as Grey_Critic says, using rad flush often creates leaks by removing the rust & crud that was blocking them up!

Last time I tried it was in The Olden Days when radiators were made out of thick chunks of brass & solder, rather than aluminium foil, glue & plastic like today. Invariably the radiator would weep coolant afterwards for weeks.

The main thing was to bypass the heater while the radflush was in, a leak in the heater matrix involves stripping the car down like those photos you used to see on the back cover of a Haynes manual with all the parts laid out.

If you had one of those Quality cars like a Jaguar, you were supposed to put Barrs Leak in the coolant when you changed it, as Olden Days sand cast engine blocks weren't particularly watertight.

Up to you what you do, with a 15 year old car I'd be inclined to dump the water, get the hosepipe to it and flush it out, then fill up with water, run until hot, let it cool a bit and dump the water, flush again with the hosepipe, then add concentrated antifreeze and top up with distilled water if you have it.

There will still be lots of plain tap water in the system though, you can't drain them like in The Olden Days.

I'd only use a flushing agent if I was sure there was a blockage somewhere, and leak fixer if I had a leak.

You don't need to add a corrosion inhibitor as that is contained in the antifreeze.

That's pretty much what I was going to be doing, just I'd planned on adding the flush. The recommendation to me was to get the rad flushed & see if this cures my issue.

So I was going to dump the existing, blast a hosepipe in there until it runs clear, fill it with water & rad flush, run it for a while, dump it, blast it some more, fill some more & run it again. Repeat this process until it comes out clear. Then I was going to 50/50 with coolant & anti freeze.


The problem I've got is when I took the cap off to top up the antifreeze, I noticed gunk inside. I put my finger in & it was like a muddy/sedimenty/oily substance.

From looking in to it it seems to be a fair split between people saying oil cooler & head gasket with a small number saying radiator crud. 

Since the radiator & coolant is the cheapest of the 3 options & the only one I'm confident doing myself, that's the one I was going to tackle.


So knowing the WHY as to why I'm doing it, you wouldn't bother with the rad flush? Just straight water?

Oh and I've got the required distilled water too.

facade

What car are we talking about? Auto or manual? Someone might know a likely cause of your problem.

Vauxhall automatics of that era and before were well known for leaks between the transmission oil cooler built into the radiator and the water, so basically the water and transmission oil changed places, wrecking the gearbox, and causing overheating.

If there is an overheating problem, I'd risk radflush, but I'd join the heater outlets at the engine with a length of pipe before putting it in as I really don't want to cause a leak inside the heater.

If it is oily gunk, a dishwasher tablet and run the engine for 20 minutes would likely sort it, but I've no idea what hot dishwasher fluid would do to all that aloominums, I'd only try it if it was that or buy a new radiator, and the car was literally an MOT away from scrap.

The danger with aggressive flushes is that the engine & radiator might leak like a colander afterwards, so you stick in some K seal to bung the holes up, which puts you back where you were before- a cooling system full of gunk and blocked small passages.

In theory K seal is supposed to only go solid when exposed to air at a leak, but I wouldn't put K seal in anything I cared about, only something I wanted to run into the ground or get shot of.

B0bbyEwing

Well I've been in touch with various owners & those are the 3 areas that they're pointing at. 

Granted, photos & videos & a nice little story are no substitute for having a look in person & doing actual tests but then that's why I prefer to ask people who are members of groups & clubs & the like because I've found over the past 20 years or so that they're actually more knowledgeable than the mechanic when it comes to these specific cars, unless the mechanic has some kind of interest in them.

For example, there's a maintenance job on these Vauxhall's that's advised to get done & can lead to trouble if it all goes wrong. Members groups know how to do this efficiently, where money can be saved & where money can be wasted & the job still gets done. I asked a mechanic & he was for taking out components that don't need shifting as well as installing a new clutch that isn't required. 

So while I obviously have to go to a mechanic to get most things done, I gather info from owners first so I have some kind of idea what may be going on.

And for this it's oil cooler, head gasket & maybe radiator. If it's one of the first two then the car can go because the list of combined maintenance & repairs is already going to be somewhere near £1k & I've only just bought the damn thing.

At least I bought it with a years ticket on it.

Grey_Critic

Sorry I did fail to say thet sometimes flushing can create a problem with the head gasket - sound like that could be a possible cause - I did many, many years ago have that happen on my MG ZB Magnette back in 1968

B0bbyEwing

Sorry I forgot to mention the heating - 

There isn't a massive issue with it currently. The blowers are warm enough for me. 

The temp gauge usually gets to temp OK. A few weeks ago where we had one cold week it struggled then. I'd drive 6 miles and it'd only be at like 60c-70c. Once that cold spell passed it was back to normal. 

Had that with my last car too which was also a diesel. Never had it with my petrols. The last car had 2 thermostats I believe & the dodgy one was an oil cooler thermostat which I had replaced & seemed to improve but not cure things. 

But I'm not changing the coolant for heating. I'm changing it to see if this gunk comes back (and then I assume the cause would therefore be the oil cooler or the head gasket.

Thats why I'm doing the change. 

Bigwheels1111

I always purchased cars with at least 100,000 miles on them, Rover 218 & 418 diesels.
Never touched the cooling system unless it leaked.
Did not care what it looked like.
Did not get up to temp.
Put some card board in front of rad, blocking half of it off to the air.
Nice toasty heat. Black cabs always do this.

Mildly_Miffed

B0bbyEwing said:

The temp gauge usually gets to temp OK. A few weeks ago where we had one cold week it struggled then. I'd drive 6 miles and it'd only be at like 60c-70c. Once that cold spell passed it was back to normal. 

That's the thermostat sticking slightly open. Changing the coolant won't help - change the 'stat.

The entire job of the 'stat is to keep the coolant away from the radiator if it's below normal running temperature - about 80degC.

Modern coolant gauges lie. They are ECU run, and only tell you if the coolant is too cool, about right (a fairly wide range), or too hot. No more, no less. Any numbers marked on the gauge are purely cosmetic. You can see the exact temperature via diagnostics, though, or a cheap IR thermometer.