MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - Question for Nigel Atkins?

Hi Nigel,
Re your comments about Hylotyte Red and thermostat gaskets
Do you run a bead of it UNDER the thermostat gasket direct to the cylinder head, AND a bead on top of the gasket so it joins with the bottom of the thermostat cover , or just one OR the other? If so which is " best"
Cheers & thanks for all your help
colin
colin frowen

Hi Colin,
do bear in mind I am not technical or mechanically competent.

I did consider if I should or not put any under the gasket and on the thermostat and head in case any broke away and caused a blockage anywhere. But as the instructions have put the red evenly on both surfaces and allow to evaporate that's what I did, same with red on gasket and housing surfaces.

Knowing me I probably put too much on, and a heavy shower that had threatened all day but held off decided to start as I was halfway through and I wondered if the rain water getting on to the head and red would cause any effect but it didn't seem to.

I use small cheap artist brushes to apply or spread sealants and greases/lubricants normally but can't remember if I done so this time or not.
Nigel Atkins

Hiya,
That's great thank you very much
Cheers colin
colin frowen

As I put I did get a leak because I didn't tighten the the three nuts enough, or the studs/washers/housing/gasket settled, or they vibrated loose with driving the car - but nipping up the nuts solved this, that another reason I like the semi-hardening sealant.

I find modern threads to be, or come, loose with use that's why I also like thread lock (and stud lock).

Perhaps decades of top-dressed road surfaces and all the pothole contribute too.

Nigel Atkins

I prefer to use the cork gasket type for this reason, you can tighten it up a bit if it does leak. They just seem more tolerant of irregularities in either surface.
GuyW

Colin, just use the gasket on its own, no sealant needed. The lesson i learnt is that if it looks like sealant is needed to fill irregularities in the metal then the surfaces haven't been cleaned and prepared properly.
David Smith

David
I do wonder about this. I'm just about to fit the thermostat housing on the Frogeye rebuild and was intending to use gasket sealant but may try without. I'll put pure water in initally so, if it leaks, I don't lose antifreeze. I used sealant on the water pump though - bit of a faff to re-do that once radiator and alternator are fitted.
Bill Bretherton

Over the years I've never used sealant, just the cork gasket and haven't had any leaks. Not that I replace the housing often. As Guy said, they forgive any irregularities and you can compress them quite a bit.
Martin

I've had a spare cork gasket for years but wasn't able to fit it as I had so few threads exposed above the housing even if I squashed the cork. When I had a change of studs I thought I might be able to use the cork gasket but still so few threads I couldn't use it.

Perhaps if the studs sold had sufficient or correct length of threads things might be easier . . . and pigs will fly.

Another paper gasket I got was so thin I didn't fancy risking it and the "quality" version of paper gasket I paid extra for and used was just about the lower end of the quality I'd want.

I didn't fancy hammering the head to make my own gasket and I'm no good at arts & crafts so couldn't scissor a decent one.

Previously I've fitted the heater tap dry and it's leaked, fitted with blue and it leaked, fitted with red no leak.

This time a mate skimmed the tap pedestal and cleaned the head so I suppose I didn't necessarily need to add red but I did and don't regret it.

Probably be better not to use these gaskets and just use a sealant but suffering is a tradition with these old cars.
Nigel Atkins

Bill,
strangely I can't remember using any sealant on the water pump when I put a new one in as part of a cooling/heating system service and overhaul but then I'd no idea what an awkward and ungrateful creature I got.

Or I might just have forgot.

The cooling system has been drained or partially drained and refilled so many times by me or others it's difficult to remember much. But the water pump has been fine, made in Turkey, apparently at the time they'd lost ship building work so good quality work was available for other parts. I do remember well that the pump was less than £13 including VAT (in 2009) because I thought about buying a Mini racing version for £20 but was told the £13 example was well made even at the price.
Nigel Atkins

Nigel
I've fitted a few waterpumps to various cars and always assumed that sealant was needed. But I don't use it everywhere. Think I'll try the thermostat housing without but I bet there'll be seepage after a few days. Just like plumbing!
Bill Bretherton

Bill,
don't rely on my memory too much!

And where I put leaks on stat and heater tap they were only really weeps but those might distract from other leaks that might appear so had to go. I have given up on the weep from the Ashley Hinton heater tap though as I've already put too much effort into it and it is a very small weep.

Original heater taps and studs present far less problems it seems than the modern replacements.

I was hoping to use my cork gasket this time but again it wasn't to be so back in stock to pass on. If you need one just shout.

Only this afternoon I found some fittings I thought I bought for the exhaust but couldn't find them when I wanted them on Saturday so assumed I'd already used them up (miss-stored, like a set of SU gaskets I thought the same about). My shed used to be so organised - but then I got this midget and the will to properly tidy away disappeared as I just wanted distraction from it! :)
Nigel Atkins

I glue the gasket to the t/stat housing with contact cement then grease the other side and grease the studs and threads--easy to remove and refit
William Revit

Why the glue, Willy? With the 3 studs a cork gasket won't wander off base like the rocker cover one does! I use a cork one with a smear of grease both sides. But the glue trick does work well for a rocker cover gasket, especially as that one is going to get removed and refitted far more often. Glue to the cover and then grease the lower edge.
GuyW

Find a paving slab, throw a little water on it, place the thermostat housing face down upon the slab and move in a figure 8. It will produce a nice flat face for the gasket and remove any pitting..
Alan Anstead

exactly Alan - or a sheet of mid-grade wet-and-dry laid on a steel or glass plate.
Just remember, no sealant of any kind was used in the factory to assemble engines so if using the correct parts and gaskets none should be required now. The only exception on my engine is a THIN bead of silicone around the sump especially on the U-shaped sump seals. A lot of aftermarket gaskets are pretty thin and naff but MniSpares do a range of correct thickness or even extra-thick ones.
David Smith

Not so David
The workshop manual says to use well seal on / between the rear main bearing cap for the MK1 Sprite. That had changed to Hylomar on the Mk2!
Alan
Alan Anstead

I think I just added the Red 100 as a belt, braces and bit of string to the stat housing as I didn't get the extra exposed thread on the studs I was expecting. I shouldn't have needed it as I did clean up the stat housing and the head was done.

I also shouldn't have needed it on the heater tap pedestal anymore as my mate skimmed it's bottom, and cleaned the head.

But then the Ashley Hinton heater tap shouldn't leak but it does, unfortunately I can't load that with Red 100.

As you don't get the correct copper washer now between tap and pedestal to allow for different orientation of tap with rounded heater box, I've added Red 100 to the copper washer there.

I found it easier to remove the Red 100 than I did the embedded remnants of the Klingersil gasket.

Obviously the real reason for using the red sealant was to detail the engine bay of my red car.

In the photos below you can see previously I've done dry installations, and the lack of stud threads.

Top part is from two years ago, with Klingersil gasket, and bottom shows how it was when I first got the car, a squashed but thinner anyway cork gasket and nuts above threads.



Nigel Atkins

I stick the gasket to the thermostat housing with Loctite gasket goo. there's a chance then that it will come off in one piece and be able to be re-used. I always use the Klingersil gasket. Be aware that there is a leak path up the studs. If you remove them from the head then gunge the treads up. I've used nylock nuts and plain washers (not spring washers) with gunge applied. Seems to be water tight.
Paul Hollingworth

Paul has reminded me that one of the reasons I used the red was because I had intended to studlock the housing studs into the head (I know, I'm a bad person) to prevent that leak path but the head was returned from having the valves and rockers check and fitted with the studs also already fitted (possibly to put me off using studlock by another that doesn't believe in it).

I also originally bought the Klingersil gasket years hoping to be able to reuse it, dry, and first time of housing removal I probably could have but fitted a new Klingersil gasket just in case. This time as the gasket surface partly embedded itself into the housing I definitely thought it best to replace and also try a different sort of gasket.

I was very surprised this last time that the housing didn't just lift off as it'd only been a few years since it was last removed and refitted.
Nigel Atkins

Alan, correct - but out of context. We were talking about in addition to gaskets.
David Smith

This thread was discussed between 23/11/2020 and 25/11/2020

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.