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1275 head on 998 block- cooling issues
https://www.ausmini.com/forums/viewtopic.php?f=5&t=35539		 Page 1 of 2
Author:  sox61 [ Fri Sep 07, 2007 6:02 pm ]
Post subject:  1275 head on 998 block- cooling issues
Hi, as stated above I have just put a 1275 head onto my 998.

Now, after a few issues :x the car is running ok. There are a few tuning issues as far as i have to run it with a little bit of choke or it backfires and basically runs like a dog... Which is fine, it's a completely different head and was expected.

My main issue is that it does not want to hold water, and it looks like it is pushing it straight out of the overflow!!!

I have used a new thermostat, new radiator cap and hoses etc. but can't find any reason for it. :evil:

I know a few people here have done this conversion, were there any problems you had?? Or anyone had this problem in general??

Any advice greatly appreciated.

Cheers,

Carl.
Author:  mattsmini1971 [ Fri Sep 07, 2007 6:17 pm ]
Post subject:  wont hold water?
hi,
maybe you have a head gasket issue. maybe you should get it pressure tested and go from there.
Author:  simon k [ Fri Sep 07, 2007 6:24 pm ]
Post subject: 
have you tested to see if the system is actually sealing?
Author:  gafmo [ Fri Sep 07, 2007 6:28 pm ]
Post subject: 
re check the rad Cap..is it the correct lenght and or seal correctly
Author:  sox61 [ Fri Sep 07, 2007 6:35 pm ]
Post subject: 
Thats what i'm possibly thinking, though i have done a compression test and all 4 are basically the same..

There is no evidence of contamination in the oil, though there was a bit of brown crud that came out of the radiator when first started. (I did have a blown gasket before, hence the new head!)

To make me a liar, the car has just cooled and i popped the cap off to reveal that there is still coolant in the top tank. :? Did it just blow out the excess, i might take it for a little drive, see what it does!

On the last drive, the temp went up to 210F. Would this be considered HOT or VERY HOT?

And for the cap, I grabbed a new one because the old one did the same thing, but i will recheck the length etc. as they didn't have one listed in their book. :roll:
Author:  sox61 [ Fri Sep 07, 2007 6:38 pm ]
Post subject: 
As for the sealing skssgn, I am trying to get this mobile guy to pressure test it for me asap, as he flushed the radiator out (tanks off i assume?) so want him to try it all in situ.
Author:  miniobsessed [ Fri Sep 07, 2007 7:44 pm ]
Post subject: 
what head gasket are you running? it should be a 1275 one (so should be the same as the head not the block) :wink:
Author:  sox61 [ Fri Sep 07, 2007 8:35 pm ]
Post subject: 
yeah I'm running a metro turbo head gasket, so have that covered thanks.

I just took the car for another drive and the coolant is still in the top tank, at the moment anyway! 8)

The temp still got to around 210F on my gauge. Can anyone let me know if this is too excessive. I might add, I usually run a thermostat that has a cooler rating, but they only had the one type across the road at sprints... I think i will change this asap.

The other thing that has happened is i am fouling plugs very quickly!
A ten minute drive yesterday- started it today and ran like crap!
I changed the plugs- again ran sweet- another ten minute drive and on the last few hundred metres, again started running like crap!

Is it possible the tune is that bad that i could foul the plugs this quickly, or by changing them, could i be just masking the real problem??

I'm having no luck with this car, any help appreciated, before she gets sent to the scrap heap :twisted:
Author:  gafmo [ Fri Sep 07, 2007 8:47 pm ]
Post subject: 
what else have you touched
Author:  sports850 [ Fri Sep 07, 2007 8:50 pm ]
Post subject: 
Just as a check , run your finger around the inside of the radiator where the radiator caps rubber seal fits and see if it's smooth and flat . It could be bent/warped slightly and causing a poor seal which would lose some of your water but not a lot quickly .
Author:  sox61 [ Fri Sep 07, 2007 9:00 pm ]
Post subject: 
Thanks guys, checked the radiator and that is fine.
As i said, on the last run, it does seem to have held the water. So possibly i had a massive air lock the first time. Not that I want to speak too soon until i have given her a decent run!

The plugs are definately shot though!!

Does anyone think it is possible i could foul them within 10 minutes?!?

First thing tomorrow i will get some more, just want to know if it is possible that's all.

Cheers.

edit: Gaf, as for touching any thing else, just the new head, radiator flush, new cap hoses & thermostat. And 2 sets of plugs!!
Author:  gafmo [ Fri Sep 07, 2007 9:31 pm ]
Post subject: 
Coiuld have had a Air Bubble in the Head..always good to pump the top hose after a coolient system change.

You could be Running realy rich..whats the exhaust while running look like due to the change in heads but still runningthe same needle. Check this and maybe lean it out a flat and run around the block and then again 1 flat and around the block again
Author:  slinkey inc [ Fri Sep 07, 2007 11:25 pm ]
Post subject: 
It is very possible to foul a set of plugs in 10 mins. Just run it real rich, I've experience this, but this was due to carby needles seat vibrating and so on and so on (all fixed now!).

:( 1275 head should work fine, the valves would have been a simliar size to your old head, yeah? Maybe you old head flowed so much better that this car is not making the power to use that much fuel and running rich perhaps?

Do you have a Gunson colour tune? If so whack that in and set the idle mixture right, might have got bumped, or moved in the head removal.

Head gasket shouldn't be an issue, I run a Metro Turbo one, always have, no problem.
Author:  sox61 [ Sat Sep 08, 2007 12:39 am ]
Post subject: 
Yeah, slinkey, the exhaust valves are the same but the inlets are 0.100" larger. I'm hoping it flows well, i paid enough for the porting etc, so if it loses power with the changeover I'll be making some calls!! I specifically said i wanted the same flow, though it wasn't tested head to head..

It's weird, the car won't run at all unless I have the choke partially out, so i thought it may be running lean (backfires if choke is in). There is definately black smoke out the back when running with the choke out.

To be honest, I can't even see an idle mixture screw just an idle speed screw which isn't long enough to reach!

If it runs ok with new plugs i will just take it to the tuners to sort the rest out, I don't have the knowledge to mess with it myself. (I can't even find the mixture screw :roll: )
Author:  slinkey inc [ Sat Sep 08, 2007 12:00 pm ]
Post subject: 
The idle mixture screw if like my HIF should be (I'm no expert on these HIFs) on the exhasut side of the carby, about halfway down, between the bottom of the carby, and the where the damper cover starts, if you get what I mean. It's on an angle, and is in a dicky place, but, well.... bad luck. :lol:

Requires a stubby screw driver and a cold exhaust (yes it dam well hurts!!!!!) So unless you really careful you have to look at the mixture turb the car off wiat till it cools adjust slightely. And repeat. Or get the tuner.
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