9 replies to this topic

[Minigman]

When looking down on a 1275 block, which holes are coolant holes?

I’ve been having issues with coolant getting in the oil quite quickly. Had the head crack tested and skimmed but still got an issue. I removed the engine from the car to block and seal the two redundant oil pump bolt holes, and whilst it’s out I thought I’d check the gearbox wasnt filling from the rad. I poured boiling water in the rad until it appeared at the face of the block. I was quite surprised it appears at all holes except for 2. I always thought the water was just in the 3 larger holes between each of the bores, but it’s in all 8 along the front between head studs too. Always thought the small holes were oil ways.

No water appeared in the gearbox so I guess the block is good but would like confirmation of the water ways if anyone knows.

Thanks.

Edited by Minigman, 19 May 2026 - 10:44 AM.

[timmy850]

These are coolant holes. The head gasket might have some more holes that don’t match the block

The oil feed is top right. Oil drains down the pushrod holes

[nicklouse]

You say “two redundant oil pump holes” there is only one oil hole visible on the top of the block.

 

a photo would help with your issue if the one from Timmy does not fully answer.

[timmy850]

You say “two redundant oil pump holes” there is only one oil hole visible on the top of the block.

a photo would help with your issue if the one from Timmy does not fully answer.

I’m guessing he’s got an oil pump recess in the block drilled for a 4 bolt oil pump, but he’s using a later pump that only uses 2 fixing bolts

Edited by timmy850, 19 May 2026 - 07:44 AM.

[Minigman]

These are coolant holes. The head gasket might have some more holes that don’t match the block

The oil feed is top right. Oil drains down the pushrod holes

Perfect, thanks Timmy850. That’s exactly where the water showed up and answers my question.

[Minigman]

You say “two redundant oil pump holes” there is only one oil hole visible on the top of the block.

a photo would help with your issue if the one from Timmy does not fully answer.

Sorry maybe didn’t explain too well. I was talking about the redundant oil pump bolt holes on the block where the oil pump sits, I removed an original 4 bolt pump and replaced it with a 2 bolt. I was concerned the unused holes had maybe broken into the water jacket when drilled back in the 60s.

Edited by Minigman, 19 May 2026 - 10:40 AM.

[Aridgerunner]

Having had two different types of head gaskets fail to seal around those water holes, allowing water into the oil, I would suspect your head gasket failed. Buy the best head gasket you can afford and follow the instructions to the letter.

[Minigman]

I’m about to fit the 3rd BK450. Fitted the first one as I’ve been doing for 35 years (which always worked) and then did the second one to the letter. Fingers crossed for the 3rd attempt.

[timmy850]

When you had the head crack tested was it also pressure tested?

[Minigman]

When you had the head crack tested was it also pressure tested?

Yes it was pressure tested. It came from a running engine so I only got it tested and skimmed by the engineering company out of desperation to resolve the issues I’m having. The engine is going back in again on Saturday so fingers crosssef this time. If it fails again I’ll pull the engine a strip the block for further investigation.