CTT with coolant usage and stuttering accleeration at low rpm

lewisweller1982 · March 25, 2016

Hi all I am new to the forum. Apologies for any mistakes............

I recently bought a 2006 CTT with 110,000km (with Porsche optional "power pack" DME tuned to 500bhp), the rough running I originally put down to lack of serving for ignition items etc, so went ahead and did the full works, air filters, oil and filter mobile1 0w-40, coil packs and plugs (Beru), and new Purge Valve (only fault code that came up) all using original Porsche parts.

The issue I have is overheating at idle and poor running, (at idle is fine) but revving and driving produces stuttering/hesitation until over 4,000 rpm and then it flies with clean acceleration. If I leave the car at idle it will gradually begin to over heat, if I rev a little it will cool back to 80oC, I have replaced the expansion cap and water pump (old pump wasn't unserviceable so I knew the end to this wasn't close yet), belt and tension and pulley all ok no slippage at idle , thought about that already).

Observations:

1. Coolant I am topping up daily with no visable leaks, I did have it vacuum bled and filled, but still the front and rear heaters are cold at idle but hot when revving to 1500rpm and above (sloshing water can be heard in the pipes that run to front and rear AC heater units because it has 4 zone climate control option).

2. no oil and water contamination either way

3. coolant DOES smell suspiciously like hydrocarbons!

4. Fans cut in and out as required all ok

5. PWIS diagnostic show no fault codes or misfires, and didn't overheat during testing unfortunately

6. Thermostat opens and top hose is hot when expected and during driving it will rest at bang middle on 80oC as expected.

7. A strange pulsing noise is audible on the left bank at the rear bulk head area which could be a whole list of things I know (exhaust leak, vacuum pipe leak, SAI leak, HEAD GASKET BLOWN and I am hearing the detonation of water turning into gas exploding!

YES I am already think the worst that is the head gasket blown.

Any body have some input or experience of the same issues please jump in.

Next step is a coolant test for hydrocarbon/ CO2 at garage tomorrow as I don't have the tester myself.

JFP in PA · March 25, 2016

Welcome to RennTech :welcome:

I am troubled by the sloshing sound you describe, which sounds like the system still has air in it. Once filled (without any air pockets), these engines should not need daily or even monthly coolant top ups; either the coolant is going somewhere, or the system was never fully filled.

A quick test to either put your mind at ease about the possibility of a major mechanical problem would be to have your cooling system tested for the presence of combustion by products. This is done by using a special system to extract the vapor above the coolant in the tank into a device that contains a liquid that changes color in the presence of combustion by products:

If you get the color change, something is given way inside the engine and you need to address that; no color change and the problem lies elsewhere. The test takes about 5 min. to run and is very accurate.

lewisweller1982 · March 25, 2016

Thanks for the reply.

Yes this is the next stage of diagnostic tomorrow at the garage.

Are the forums usual this quiet? Or is this a time difference case for many users?

JFP in PA · March 25, 2016

Thanks for the reply.

Yes this is the next stage of diagnostic tomorrow at the garage.

Are the forums usual this quiet? Or is this a time difference case for many users?

This is a holiday weekend here (Good Friday, Easter Sunday), and some forums tend to see less traffic over holidays.

clarksongli · March 27, 2016

i think you might have two separate issues that just happen to be happening at the same time. I had nearly the same issues....

So i had my coolant Tee's break so i had to drain a lot of the coolant to change. Well i refilled and vacuum bled but was driving around and i kept losing coolant with no sign of where it was going. At the same time i had a bit if a stumble and semi rough idle. Instantly i thought the same thing as you.

Long story short. Even with the vacuum bleed, the system was still self bleeding, about 2 weeks after the coolant level stopped dropping.

My stumbling was actually coil packs. I had just checked them, but when i pulled a few to double check, they nearly all had split. A new set of coils and it idles/drives like normal again.

Do the hydrocarbon test, but pull some coilpacks and inspect. you might be seeing the same thing i had.

lewisweller · March 28, 2016

Hi clarksongli

Update is head Gasket failure, I'm buying all the parts now from USA and having them shipped over to uae. Quote

is $6000 parts and labour but I can get that down to 3500 if I buy the parts.

Will also be doing some other PM tasks like transmission service and mountings including the auxiliary water pump. Should be like new after hopefully.

lewisweller1982 · April 20, 2016

After spending about 5,500 USD I have now have a CTT 2006 (with E81 power kit from new) that has new head gasket, new valve stem seals, machined and skimmed head and newly ground valve seats, new gaskets, temp sensor, thermostat, a load of new pipes fittings vac etc, new aux belt, tensioner, idler rollers, water pump and pulley, cleaned alternator full of oil and sh*t...................I think your getting the picture, total nightmare

Also found transmission mount split add 3 new please .............ATF, transfer case and F&R diff oils all changed, new plugs and Ignition coils, new battery, home repaired Kessy unit and rear lights. Few; I need a holiday but im skint.......

So when I get the car back tomorrow or Friday, I hope its running like a dream or I might torch the thing!!