Water pressure problem! Plz help

[sr nova boi]

Hi all, I have recently fitted a rebuilt engine in to my 1991 nova sr 1.4. The engine is still a 1.4 but has a big valve head, piper 285 cam with a Kent vernier, facet fuel pump with a webber fuel regulator and a 4 to 1 manifold. I was told when I bought it that it had already been run in for 1000 miles but decided to run it in for a further 600 miles before venturing up the rev range! Basically the other night I was giving it run down a local B road and I heard a weird rattle and then lost all power. When I popped the bonnet the header tank cap was sitting behind the firewall and nearly all my coolant had emptied over the engine. Im worried some of the water went into the oil breather as it didn't want to start and don't want to try it again until I have some advice! Could it be the water pump? It was new when I put the engine in 3 weeks ago) but it had sat up out of the box for a year. I'm at a loss so any help would be greatly appreciated, thanks Rob

[mowgli]

fill it back up, & tighten the cap properly, and run it up to see if it runs ok before doing anything rash.

[phunkynova]

If it's blowing the coolant out then normally its the head gasket gone, as it will be letting the compression from the cylinder/s into the water gallery's.
But maybe some one else has a better answer.

[garyc]

it could be overheating due to incorrect fueling\ ignition timing set up. If it hasnt been set up properly then this could well be the case.

[C612DNM]

Weird rattle? Could be detonation caused by water getting into one or more cylinders, which would also explain pressurising of the coolant system, and blowing the cap off.

You could do all of the usual/simple checks for water breathing - wet plug(s), clean/shiny exhaust ports on the one(s) that is in trouble, and if you know someone that has one of these funky bore inspection cameras, you can have a look inside down the plughole before you commit to take the top off.

[Southie]

I had this happen on a old 1.4sr when my heater matrix was blocked, I only really found out it was knackered though when going down the outside lane of the motorway when it exploded :eek: