The Triumph Dolomite Club - Discussion Forum

First time I used Hermatite Red which I have always used the last dozen or so times I have done this.

Second time I used a silicon instant gasket type sealant, waited 48 hours before filling & still a failure.

This is the first engine I have worked on with a Weber type inlet manifold, every time before has been with a standard manifold, so I think the problem lies with the manifold. When I took it apart the tube/manifold had a lot of sealant on, so I think there has been a problem before.

When I remove it I will take some proper measurements of the manifold & pump cover to see if there is any difference in diameter which I know there will be, then see if I can get a thicker O ring to suit, or get a custom tube machined.

I agree that the O rings alone are marginal, but I don't think that on this manifold standard O rings & sealant is going to work either.

Tony Burd wrote:I think the problem lies with the manifold.

That would be the problem. It has come up before on the forum.

I have not had to work with one of these Weber manifolds so don't know an answer.

However what I will say is that you are supposed to use silicone grease on the rubber O-rings to aid fitting.
It doesn't tell you that in the workshop manuals because you are expected to already know this.
Similarly you should steep brass spigot bearings in engine oil, use engine oil on head studs, etc.




Ian.

yes, actually looking at the manifold it doesn't appear to line up very well as if it's wonky. I had forgotten you'd gone Webers. As you say the sealant trick is fine but perhaps maybe wouldn't work in this situation as it is too big a gap or alignment issue.

I've had the inlet manifold off and on several times in the past few years (1850) and always fit new O-rings with a smear of rubber grease, silicone grease or vaseline if desperate, pushing the tube through the thermostat housing after the manifold is fitted.
The only problem I've seen (twice) is when filling the system having forgotten to fit the bloody tube at all!!

Edin Dundee wrote: The only problem I've seen (twice) is when filling the system having forgotten to fit the bloody tube at all!!

Cheers Bill that made me laugh!

These weber type manifolds don't have the hole for the bypass tube accessible from the thermostat housing unfortunately, so you can't push the tube through once the manifold is fitted, so it is a bit of a juggling act fitting the tube, inlet gasket & manifold.

I am wondering if it may be an option to have your Weber manifold plugged and then drilled again to make the hole align
that of the water pump cover properly? Thereby you could use a the normal bypass tube and O-rings.

A Sprint HS6 manifold could be used to get the correct position for the hole....






Ian.

Could be a last resort option, Ian, making a new tube will be easier.

Will see how it goes once I get it apart, will look at sourcing some alternative O rings first, see if I can get some slightly fatter ones.

We have the 'O' rings in club stock. I can measure them to see if they are any different from the ones you have Tony.

Please Mart that would help especially the cross sectional diameter.

Cheers

Tony

CS is 2.6mm.
O/D is 23mm.

Ta, same as Rimmers & Robsport.

Took today off work to try to sort this bypass tube problem.

Removed the inlet manifold & carbs for the 3rd time & took some measurements

Water pump inlet diameter = 21.2mm
Weber manifold inlet diameter = 22.8mm

O ring diameter when fitted to the bypass tube 23mm, so there is a 1.8mm interference fit into the pump housing but only 0.2mm into the manifold hence the problem.

Went down to my local engineering supplies to have a route through their stock of o rings, couldn't find anything suitable, but instead they sold me some 3mm diameter rubber cord, so I made my own o ring.
I used a razor blade to get a nice clean cut, then super glue to stick it together;




So with my homemade o ring fitted I now have a diameter of 24.1mm at the manifold end, which gives me 1.3mm of interference, which is 0.5mm down on the pump end, but well worth ago.

So just got to put it all together again & see what happens.

Fingers crossed & toes & everything.

Left the manifold reassembly until the weekend, just cleaned & fitted lots of the door & interior bits, plus fitted the rear screen

I used speaker wire to pull the rubber over the lip, worked a treat

Still got the trim to fit, does anyone know if you can get it in black rather than chrome?

All back together & no leaks!
The homemade O ring has worked.

I was so pleased this problem was sorted, I treated the car to it's front spoiler.

Bonnet & number plate on, we'll see what the MOT man has to say about the stick on plate, but if E types get away with it, don't see why a Dolomite won't.