The Triumph Dolomite Club - Discussion Forum

Morning All

I did a 50 mile motorway drive yesterday, a steady 70mph car behaved perfectly. When i got home and turned the car off a gush of fluid came out of the overflow pipe on the coolant bottle.
Any idea as to why it may have done this? It is serious?
Thanks

I know very little about cars, but my Dolomite was dumping coolant after fairly standard drives back in 2007. I didn't think much of it, thinking I'd get around to getting it looked at and would just keep topping it up as required.

A few trips later I then set of to drive from Nottingham to Hertfordshire, but never made it. The engine started making a horrible noise and when I pulled over in a service station to look at it, it wouldn't start up again. I would later be told the 'big ends' had gone and it's been off the road since.

I'm not saying, or know, it's the same thing... but I'd get it looked at.

Phil

Coolant coming out of the overflow bottle generally indicates that the engine is overheating. It could also be caused by the pressure cap operating at the wrong pressure.

You want to identify the cause asap, on the models with alloy heads the overheating can cause the head to warp. I wouldn't drive it until you've identified the problem.

Yes, the big ends failing could be a cause - the increase in friction causes extra heat which causes the coolant to boil.

Also, check the pressure cap is sealing properly.

In edition 211 -the October - November 2022 edition of Dolly Mixture I did write an article on how to test your pressure caps. In the article I was working on a 1500 type. I know the sprint pressure cap is somewhat different but I assume the same set up would work. It is quite cheap and simple to do. One thing to remember is that there are in fact two valves in the pressure cap. The main one we think about is the one that should hold pressure until the pressure reaches the caps release pressure. The other valve is there to let air into the system when the engine is switched off and the system cools down.
It took me some time to work out where the second valve is in the pressure cap but if you look at the attached photographs you will see that it is at the bottom of the pressure cap as I have used a length of wire to hold it open.

This is fairly common, the car will run fine whilst being driven and coolant is circulating. Switch it off and suddenly the water is no longer circulating, local hot spots in the engine heat the water beyond boiling point and the pressure defeats the cap.

It's usually the first sign of a failing rad cap/cap seal, which is where i'd look first, caps being cheap! Make sure you get a good quality cap (as with everything else, there's a lot of rubbish about) and pay particular attention to the seal ring if it's a plastic header bottle - a known weak point.

IMO the next most common source is probably a partially blocked radiator core. This is a bit harder to be sure about. With the engine warmed up, feel the core all over to make sure there are no cold patches. It's not easy! If it's a Sprint, also make sure it has an actual Sprint radiator fitted. There was a time when several suppliers were selling 1850 cores as Sprint, which turned the cooling system from adequate to marginal. You actually have to count the core vanes to tell, IIRC its something like 24 in an 1850 rad and 28 or 29 in a Sprint core. No doubt someone will be along soon enough to gleefully correct me if i'm wrong!

Steve

Yeah it didn't happen immediately, i turned it off and maybe a minute or so later i heard the splash.
I've been advised to first put a dual value Thermostat in, then check the cap pressure on the coolant bottle, actually the coolant rubber cap is old, thin and split could this add to the issue?

Also since i had the car the temp gauge would go to 3/4 quite quickly i also have a feeling the fuel gauge reads high, I have put a new voltage stabilzer on it and check all readings, now thinking would it be a faulty thermostat causing the temp gauge to read high?

How can you tell the difference between a sprint and 1850 rad?

jlan1978 wrote: ↑Tue Apr 04, 2023 9:06 pm How can you tell the difference between a sprint and 1850 rad?

You can easily see through an 1850 rad