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Can I ask a non-MX5 question? My daughter's 1997 323 BA 1.8 seems to have a head gasket problem. On longish drives - over an hour - the coolant bottle overflows. The system is clean and maintained well (by me). I suspect pressure from a cylinder is leaking into the cooling system - not good! My assumption is the only fix is to remove the head and replace the gasket - not something I have time to do at the moment as I'm going OS.

Anyone have experience with these motors? I was going to be doing the cam belt etc soon anyway so it looks like I have a bigger job on my hands.

Thoughts, comments and most particularly any idea of where to get a manual for the engine, very much appreciated.

Regards and thanks in advance for any help.

Tim

Coolant bottle overflow is one sympton of a leak across the head gasket from a cylinder to the water jacket. Typically you'll also see microbubbles in the coolant. Take the radiator cap off when the engine is cold and let it run with the cap off for a few minutes. If the leak is there then the coolant may bubble up when you rev it or it may just become frothy or milky. Compression test and exhaust gas (CO) analysis of the coolant at your local mechanic will confirm it.

I've got a 92 BG 323 service manual for both SOHC and DOHC in PDF but not a BA one. I'm not sure of the differences between BA and BG though. PM me your email address if you want that.

I've done a head gasket replacement for the BG SOHC. It was a pretty simple job if you've done head replacements before. Be aware that if the engine has boiled badly then the head metal may have softened and the head is a write-off.

manga_blue wrote:I've got a 92 BG 323 service manual for both SOHC and DOHC in PDF but not a BA one. I'm not sure of the differences between BA and BG though. PM me your email address if you want that.

I've just put it in my dropbox. You should be able to download it from there in about an hour if you want it.
https://dl.dropboxusercontent.com/u/890 ... ervice.pdf

You should also be able to find some specific information/help over on the AstinaGT forums.

http://www.astinagt.com/forums/index.php

Theemostat stuck shut?

Also have a look at the water pump.

The old pump on my car had a lot of calcium deposits on one of the ports which meant the coolant would pressurise on one side and make the overflow bottle REALLY overflow after a decent drive. (previous owner must have used some pretty hard tapwater)

A new pump and it all stopped.

Many, many thanks for the replies. The engine does not appear to overheat - at least according to the temp guage - if that can be relied on for anything. If the thermostat were stuck I would expect overheating. If I get time before going OS I might take it off and check. I was going to change the water pump with the timing belt etc but had not considered that it might be the issue.

The first thing is really to confirm that it is the head gasket.

Regards and thanks again, this is a fantastic forum.

Regards,

Tim

Bear in mind the thermostat will only cause overheating if it sticks closed.

If it sticks open the car won't overheat, but you may notice it runs cold at speed. (since normally as the coolant temp drops with the fast air going through the rad the thermostat will close to keep the engine warm, then open once it gets too warm, etc)


Personally i'd replace the thermostat anyway, they're only $15 or something so I don't even bother to check them unless it's only been put in recently.

I'd be inclined to leave it at a workshop and just enjoy the trip. This would be pretty much bread and butter work for any decent local business. Do the diagnosis, timing belt, water pump and maybe head gasket all in one hit.

manga_blue wrote:I'd be inclined to leave it at a workshop and just enjoy the trip. This would be pretty much bread and butter work for any decent local business. Do the diagnosis, timing belt, water pump and maybe head gasket all in one hit.

This is my daughter's car and she's an impoverished student. I actually have all the equipment to remove the engine and transmission if necessary - I hope access isn't that much of a pain and I 'm happy to do it for her. It's fine on shorter drives (at the moment, of course things can get worse - they tend not to get better). I was wondering if I ought not to check the torque of the head bolts at least before I go.

Tim

Not much different to a NA6/NA8 engine. It is just transaxle and easier to get out. Inturnaly it is the same as a NA8 engine, just had different cams and solid lifters. But you shouldn't be touching those for the job you wanna do.

But if you do wanna check the head bolts, 76-81Nm is what you need to aim for. And you need a 12mm 12 point socket piece.