The DIY Head Gasket thread - info collation + help request!

You are too generous - I wouldn't say no if the offer is there, kind sir!


re: the coolant reroute, I'm sorta of the same viewpoint as you, Rich - I'm not sure there's been any back-to-back testing with empirical data on engine temperatures and warming/cooling cycle speed?

I do have one of the chunky aluminium radiators, on the basis my standard one was blocked to the point of everything overheating, and while it was being replaced I thought I might as well 'upgrade' (with comments re: standard parts being good for a decade or more noted )

Mine always stays rock-steady in the middle with the aluminium rad - I know the capacitors in the dash are designed to not move the dial unless things are getting considerably hotter, but it doesn't move even in super-hot weather.

It could be worth sticking a dedicated thread/question up, as the discussion might get lost amongst all my waffle in this thread lol

Tbh, you only need that pin when tensioning the belt (IF you are using the Mazda one ‘spring’ tension?) it’s for the tensioner to ‘arc’ around under spring pressure to set belt tension.

Could wonder if it was ever there & if it was where did it go?

If there’s nothing wrong with the pump you can just use a pin / Allen-key to act as the pivot to set the belt tension and once the tensioner-pulley bolt is tight remove the pin etc?

^^sorta what I’d do

Anyway, as to pumps... this one has been on my eBay watchlist for a few months.....
rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F372664283495

Also local to me (& nothing to do with me) but that don’t help you

£9.95 posted....

Rich.

It's an interesting point you raise. I also have never seen any evidence or test results that demonstrates the effectiveness of the coolant reroute. All I've seen is internet bro science and anecdotal evidence.

If you read a popular US based MX5 forum, it would seem the reroute is a mandatory upgrade for any high power MX5. However, I have strong reservations about accepting any advice
given on that American website. This is because the most prolific posters giving that advice are either forum moderators, sponsors, or vendors. The products recommended are usually those sold by the moderators, sponsors or vendors. To the point that new forum users are bullied for not using the recommended products, and any non approved item, product or company is often dismissed out of hand.

Back to coolant reroutes, measuring the effect of rerouting the coolant system would not be difficult to do, just expensive. You could modify a cylinder head to accept an array of thermocouples inside the coolant jacket, probably positioned to measure the coolant temperature near the exhaust valve seat.
You could then run a back to back test with and without the reroute, making sure to control the engine speed (and therefore pump speed), engine load, coolant medium properties, and coolant temperature (which the thermostat should handle). The testing would almost certainly have to be carried out on a dyno to allow the engine to be held in a steady state condition long enough for temperatures to stabilaise.

I think the real reason that there is no tangible evidence proving the effectiveness of the coolant reroute is that the measuring, recording, analysing and presenting of data is prohibitively expensive. Especially for small companies.

If you look at the designs of the mk1/2 and the VVT head gaskets, mazda changed the later gasket on to alter the flow around the engine, which suggests that the earlier design wasn't the best - manufacturers don't spend money on things like that unless there's a need. It also means a reroute is a bad idea if you are using a VVT head gasket, you'd need to swap to an earlier model one (or drill out the blanked ports). 

If you are building a high power car and/or something that's going to spend a lot of it's life running hot (ie. track car), the reroute makes sense logically from a heat management perspective as it's a straight path through the engine, not in and round and back out the front again. If you aren't planning on extreme use, then it probably doesn't make much difference. 

From what I remember, and it's been a fair few years now, when I did the reroute it dropped the temperatures I was seeing on the hot side of the rad by several degrees (aftermarket gauge). You also don't need to spend a fortune on a pre built kit - you can make your own using a mixture of mazda bits that will run you to about £20 + good quality rad hose.

Thanks for checking in!

Sadly still static


Work and commuting and various appointments/commitments have kept me busy, and then the weather always rains when I get some time (like this weekend, for example - downpours forecast!) so it's still no further

If it does buck-up over the weekend I'd like to get some done!