Your K-Seal success /failure stories

[DavidB]

I’ve only used this stuff a few times and I’ve had varying results, it mostly worked, and sometimes did nothing, but never blocked the heater matrix/water passages.

I rebuilt a k-series once and put it back in the car and found it dripping coolant down the back of the block even having checked the head bolts were correctly torqued so threw the towel in and put a bottle of k-seal in and it ran perfectly for about four years before I sold it.

[twosmoke300]

Can we add Steel seal into this . 
 

 

It succeeds in only one thing - blocking up every coolant passage and making subsequent repairs a proper cunt .

[Wibble]

I asked my local classic friendly garage about this when I had a coolant leak. His opinion was don’t go near it with a modern engine but that it could be quite successful with older stuff. Agreed it was worth a try with my Cortina, which we reckoned was leaking from a core plug,  which would require gearbox and clutch removal to access. Result? Hasn’t leaked since and no other problems to report.

[Neil clark]

Did about 40k miles in a peugeot with this in, it worked

[rusty_vw_man]

Worked well for me, but only for the rubber head seal in a VW waterboxer engine . 

[RoverFolkUs]

Don't fucking bother 

Unless it's a last resort before scrapping the car, it just bites you in the arse when you come to do the job properly 

[plasticvandan]

33 minutes ago, twosmoke300 said:

Can we add Steel seal into this . 
 

 

It succeeds in only one thing - blocking up every coolant passage and making subsequent repairs a proper cunt .

I worked for the absolute shark that imports this shit some 15 years ago,no,it doesn't work,yes,it will kill your engine and block everything up.

[Stanky]

I only discovered it was a 'thing' too late. I had a lovely mk1 Fiat Punto 90 elx which was a great car, but blew its head gasket after about 4 months of owning it. I ended up part ex'ing it at a bombsite car trader near Fratton Park football ground in about 2007. I did see it about later, but only a couple of times so I suspect it got scrapped. 

The Mk3 golf CL I got in PX for the punto soldiered on for about 3 years but the heater matrix began to weep coolant and fearing a 90c face, foot and hand wash if it properly let go, I bypassed the matrix on the engine side of the firewall. This meant I had full control of fan speeds, but no heat. It was OK in the summer, but the winter of 2010 was fucking cold, and the thing wouldn't heat up. In the frost, the inside of the screen froze, and when it was raining it steamed up something chronic so I ended up selling it for a few hundred quid to a guy for his son to learn to drive in. I'm not sure what happened but it got scrapped soon-ish after. Whether he replaced the cambelt (due on miles) and windscreen (had a giant crack in it) before he discovered the heater matrix issue I don't know - or maybe the son wrapped it round a tree?

Anyway, the point being that to this day I wonder if either of these could have been given a few more years of life if I had known that K-seal was a thing. In both cases it wouldn't have made the situation any worse even if it hadn't made it better. 

[twosmoke300]

3 minutes ago, Stanky said:

I only discovered it was a 'thing' too late. I had a lovely mk1 Fiat Punto 90 elx which was a great car, but blew its head gasket after about 4 months of owning it. I ended up part ex'ing it at a bombsite car trader near Fratton Park football ground in about 2007. I did see it about later, but only a couple of times so I suspect it got scrapped. 

The Mk3 golf CL I got in PX for the punto soldiered on for about 3 years but the heater matrix began to weep coolant and fearing a 90c face, foot and hand wash if it properly let go, I bypassed the matrix on the engine side of the firewall. This meant I had full control of fan speeds, but no heat. It was OK in the summer, but the winter of 2010 was fucking cold, and the thing wouldn't heat up. In the frost, the inside of the screen froze, and when it was raining it steamed up something chronic so I ended up selling it for a few hundred quid to a guy for his son to learn to drive in. I'm not sure what happened but it got scrapped soon-ish after. Whether he replaced the cambelt (due on miles) and windscreen (had a giant crack in it) before he discovered the heater matrix issue I don't know - or maybe the son wrapped it round a tree?

Anyway, the point being that to this day I wonder if either of these could have been given a few more years of life if I had known that K-seal was a thing. In both cases it wouldn't have made the situation any worse even if it hadn't made it better. 

Wasn’t there a free recall on golf heater cores ?

[Stanky]

Just now, twosmoke300 said:

Wasn’t there a free recall on golf heater cores ?

I think that might have been Mk2s maybe? TBH at that point I was working a shit deadend job and earning an absolute pittence - with a 1 year old and was the sole earner! The golf needed the matrix replacing, cambelt and water pump, the screen replacing, a wheel bearing and various other things I have forgotten! Even if the heater matrix had been FOC under recall it was still £600 of work which was about £597 more than I had to my name! I sold it and we became a 1 car family for a while until I had saved up £400 and bought a N15 Nissan Almera which was a cracking car and probabaly one of my best ever buys. It never went wrong, was easy to fix, did mid 40s to the gallon and was surprisingly comfortable with front seats from a GTI model fitted.

[twosmoke300]

2 minutes ago, Stanky said:

I think that might have been Mk2s maybe? TBH at that point I was working a shit deadend job and earning an absolute pittence - with a 1 year old and was the sole earner! The golf needed the matrix replacing, cambelt and water pump, the screen replacing, a wheel bearing and various other things I have forgotten! Even if the heater matrix had been FOC under recall it was still £600 of work which was about £597 more than I had to my name! I sold it and we became a 1 car family for a while until I had saved up £400 and bought a N15 Nissan Almera which was a cracking car and probabaly one of my best ever buys. It never went wrong, was easy to fix, did mid 40s to the gallon and was surprisingly comfortable with front seats from a GTI model fitted.

But it’s a German car ! That’s all just maintenance and not mentioned when rubbishing other countries cars 😂

[Marshall2810]

Shittt

[RoverFolkUs]

17 minutes ago, Marshall2810 said:

Shittt

After directly flushing it through with a wet and dry vacuum cleaner and a hosepipe, as well as plenty of complete system flushes using dishwasher tablets, I'd say the heaters are now 75-80% of what they should be. Not furnace hot, but hot enough 

[sierraman]

Used it loads of times as it’s never failed me. 

[Angrydicky]

It’s an end of life bodge to use on a car that’s on its last mot. Just fix it properly ffs.

[sierraman]

1 minute ago, Angrydicky said:

It’s an end of life bodge to use on a car that’s on its last mot. Just fix it properly ffs.

Just depends, if it’s a straightforward seal or something needs replacement or the radiator or whatever then I’d just do it. But used it on an external head gasket leak on a Corsa - this was 2 years ago, stopped the leak and it’s been fine since. Was I going to start taking the head off it in February outdoors? No… 

Also had a thermostat housing go, the replacement housing no longer available as a factory one only the cheap ones you could get, couldn’t get it to seal 100%, stuck some K-Seal in and it sorted it for the year or two I had the car before I sold it. 

[sierraman]

10 hours ago, twosmoke300 said:

But it’s a German car ! That’s all just maintenance and not mentioned when rubbishing other countries cars 😂

Just a straightforward cooling system refresh. They’ll run forever. 😂

[bangernomics]

Tried it on a J5 that I needed to drive back from dorset to manchester. Didn’t work and it took me 12 hellish hours or so filling it up every 60 miles after it shit its water out.

Was fine after a head skim and gasket set.

Had the replace the rad and it had blocked it up.

[N Dentressangle]

Is Radweld / Bars Leaks the same stuff, or slightly different in terms of gunging potential?

[Leyland Worldmaster]

1993 BMW 730 had water in the oil. Changed oil and put K Seal in with the coolant.

No more mayo and the heating wasn't affected. 

[sierraman]

5 minutes ago, N Dentressangle said:

Is Radweld / Bars Leaks the same stuff, or slightly different in terms of gunging potential?

No, it’s much better than those. I remember Bars leaks came in a plastic container that resembled an old style radiator! 

[N Dentressangle]

15 minutes ago, sierraman said:

No, it’s much better than those. I remember Bars leaks came in a plastic container that resembled an old style radiator! 

That's right! Filled the system with flecky coppery looking stuff. Groovy.

[BorniteIdentity]

I would 100% roll the dice on a car that was end of life. I used something called Tec2000 in a Raver 75 and it gave me another 10,000 miles.

The car was worth £800, I had a straightforward choice between a £15 bottle of potion or £500 on a head gasket etc. 

It worked brilliantly. 10,000 miles later I stuck some more in which bought me another 10k. At that stage I put one more bottle in and sold the car on to someone. It was still running well at the moment he stacked it and wrote it off. 

Depends on your attitude to the car. I’d not use it on the sierra, but a disposable daily? 100%

[GeordieInExile]

Is it called K seal because it was invented to assist the thousands of grateful Rover owners who suddenly found themselves in need of such a product when the K series was launched?

[Rust Collector]

I used it on a 1.6 mk2 golf, it did nothing and I ended up doing the HG. No slushing of waterways noticed, and the engine is still in my garage now despite the car being cubed.

I used Holts Wondarweld in my V6 Shogun Sport, which was spraying boiling coolant out of what I suspect was a rotten core plug at the back of the block. Engine out job to replace, it was a £550 4x4. After K seal failing on the Golf, I expected fuck all. However, it fixed the leak and I used the 4x4 for quite a bit of towing that summer - it never failed again. No idea of the longevity as I’ve stopped using that 4x4 since, but I’d use that stuff again on a cheap shitter, if I was in a bind.

If it’s a job where it can be fixed properly without losing the will to live, then I’d still avoid it - was tempted to chuck some in the XM but I persevered and tracked down and repaired all the leaks instead.

[Tommyboy12]

I've used it. It blocked up the leak but it also blocked up the heater matrix (I presume) as it stopped being a heater

[24vdiamond]

I used it in a £500 Astra G auto, the rad was leaking which is specific to the autos and at the time a replacement was £140, a bottle of the coppery K seal and it lasted another 40,000 miles before the rad was too rotten and I found a sensibly priced replacement!

Its still fine now with no ill effects apart from a slightly smaller cam lobe which I cant blame on the K seal 😁

[sierraman]

3 hours ago, BorniteIdentity said:

I would 100% roll the dice on a car that was end of life. I used something called Tec2000 in a Raver 75 and it gave me another 10,000 miles.

The car was worth £800, I had a straightforward choice between a £15 bottle of potion or £500 on a head gasket etc. 

It worked brilliantly. 10,000 miles later I stuck some more in which bought me another 10k. At that stage I put one more bottle in and sold the car on to someone. It was still running well at the moment he stacked it and wrote it off. 

Depends on your attitude to the car. I’d not use it on the sierra, but a disposable daily? 100%

I can’t believe you didn’t contemplate taking a week off work and changing the head gasket. 😂

[danthecapriman]

I’m loathe to use it tbh. If it’s a shit heap that’s at deaths door anyway and you need a quick easy fix then fine, but I wouldn’t use it on anything I wanted to keep or look after.

Someone had used it in my Volvo many years ago for something. When I got the car it wasn’t leaking and hasn’t since so it obviously worked but it also blocked the heater matrix solid. Absolutely no heating whatsoever. 
Only way I managed to sort it was stripping as many hoses as possible off the cooling system and constantly flush and back flushing the block, radiator, hoses and heater. The heater must have been packed absolutely solid as even rigging up a big long hose directly into it from the outside tap on the house struggled to clear the blockage! 
In the end I had to just let it pressurise as much as possible from the tap which did eventually blow a mass of coppery rubbery greasy crud out of the heater! 
It was flowing that stuff out of everywhere for ages though when I flushed it. Since then the cars had two coolant changes and yet there’s still tiny traces of the coppery rubbery shite in the system. 
 

Im of the opinion that if something is leaking it’s because something is broken so fix it properly!

[Scruffy Bodger]

On 19/01/2025 at 08:38, Angrydicky said:

It’s an end of life bodge to use on a car that’s on its last mot. Just fix it properly ffs.

For someone who only ever runs end of life cars it's a great fix. I've used it multiple times on cars when the heater matrix has sprung a leak. Fuck taking the entire dash out to change one, stick some of that in and job jobbed.

If the leak isn't too bad don't stick the whole bottle in. It's also handy when a radiator springs a leak after the initial problem as it stops it before it gets too bad. This was thoroughly tested on a Mk5 Cortina that ended up as a field car, we ended up moving the rad to where the back seat should have been, suspended on a spiders web of bailing twine as we kept damaging it.

I finally killed it when I snapped the gearbox off the engine but it was still holding coolant!