Two Big Problems with my Turbo car

Marcone · 12-19-2007, 07:50 PM

Had the car inspected today...

Compression problem in one cylinder... the other 3 are exactly the same yet one is half the compression of the rest.
Car does not idle weird or anything... but leakdown says that there is either a burnt exhaust valve, or bad spring.

Clutch is near dead

Timing belt is due

About 3k in parts and labour is needed. (seals, clutch, gaskets, valves)

Second big issue is....

driving home.. near empty ..needed gas.. only could find 91 octane, put about 10dollars in (canadian) and start driving and i hear the turbo a LOT louder and the idle is horrible.. down to almost 400rpm and back up to 1100 sits for a sec and back down.. but never died..

is this octane related?
what should i do about the valve issue while im in there... i usually upgrade things when stock brakes... why not go in a little deeper while youre already in it..!

Thanks

Marcone

JoshB · 12-20-2007, 05:10 AM

Man - hopefully that bad compression is not a scored cylinder. That would mean your block is basically a boat anchor.

Better keep your fingers crossed that it is headgasket or valves.....

I would pull the head and have a look.

AaronM · 12-20-2007, 08:35 AM

91 octane should not cause a problem. I ran 91 during my trip through California because that's as good as it gets there and the car ran fine the whole time.

It definitely would not cause a problem with the idle.

blown 944 · 12-20-2007, 08:58 AM

Easy way to check out the cylinder is to use some compressed air at TDC on that cylinder.

once you get a fitting that will allow you to use about 80-100 psi you should be able to hear where it is coming from. like listen with the TB tube of and see if it is an intake valve , listen from the aos tube to see if it is blowing through the rings or cylinder and then listen out the exhaust to see if it coming through an exhaust valve.

You will also be able to tell if it has a blown HG b/c it will push coolant out the reservior.

However I personally would just pull the head and look at everything. easier to be sure.

Since you have to do the clutch, just drop the engine and cradle and kill a few birds with one stone.

Marcone · 12-20-2007, 12:23 PM

I think every one missed it..

We DID do a leakdown and found out its from an exhaust valve.. whether its the actual valve that is burned/chipped or its a spring not working on that valve is the question.

LOL

SO.. i should drop the engine and do it all that way.. i was gonna send it to the shop and do it.. im scared of the turbo stuff.. dotn know it that well.

So secondly the octane shouldnt be the issue.. therefore maybe the leakdown damaged the valve even more?

Lemme know if you know anything

Marcone · 12-20-2007, 12:24 PM

I think every one missed it..

We DID do a leakdown and found out its from an exhaust valve.. whether its the actual valve that is burned/chipped or its a spring not working on that valve is the question.

LOL

SO.. i should drop the engine and do it all that way.. i was gonna send it to the shop and do it.. im scared of the turbo stuff.. dotn know it that well.

So secondly the octane shouldnt be the issue.. therefore maybe the leakdown damaged the valve even more?

Lemme know if you know anything

nize · nize's Garage

if the only problem is the exhaust valve, there is no need to drop the engine. just remove the head and install new valves.

Marcone · 12-20-2007, 08:01 PM

A little scary the amount of pipes and wiring that goes with this cramped space...

i was cool with the Bmw 6cyl.. but this seems more complicated... probably gonna send it in.

blown 944 · 12-21-2007, 04:52 PM

You should do it. If you are going to look at building some big HP you should be familiar with everything anyway. Guessed I missed that it was verified that it was an exhaust valve.

It's really not that hard .

You are going to needa clutch anyway.

I would still drop the engine

Marcone · 12-21-2007, 05:13 PM

Ok... well if i get it out and take it apart myself... which i have done before with the S and S2 models.. and a few beemers.. Im ok with the dis-assembly and re-assembly stuff with normal engines.. might as well bite the bullet with the turbo motor as well...

what should i do to the head to make it better.. if i am sending it in to a head guy anyways to do the valves.. will an angle job help etc... ? Any tips? for the while youre in there obsession i am going to have while i am in there !hahah LOL

Techno Duck · Techno Duck's Garage

The turbo motor really isnt all that more complicated than the n/a cars with the exception of a few more coolant lines and vacuum lines...and yes spaces are a little more cramped, but its really not bad.

As for the cylinder head, replace the valve guides, and valve stem seals. Have them check for flatness of the mating surface and machine it flat if necessary. Valve jobs really arent necessary but 3 angle or 5 angle valve job couldnt hurt.

soxnail · 12-22-2007, 06:58 AM

Did the problem with the idle just start ? (after the fuel stop).
Sox

Marcone · 12-22-2007, 07:10 AM

Yes.. did the compression and leakdown test.. drove 20 miles fine... got very near empty which is not a normal practice!...got gas.. now have idle problem.
Havent driven since.
Any ideas?

soxnail · 12-22-2007, 07:48 AM

Could have sucked in some junk into the fuel filter ? Is it surging or just rough ?
Sox

nize · nize's Garage

do not forget the steam vent mod while you have the head off. one of the best mods i've ever done;

http://www.lindseyracing.com/mm5/merchant.mvc?Screen=CTGY&Store_Code=LR&Category_Co de=STEAMVENT

Marcone · 12-22-2007, 02:49 PM

Surges ...

Thanks about the steam mod.. never even heard about it.

Marcone

Luis de Prat · 12-23-2007, 12:23 AM

Quote:

Originally Posted by Marcone

Yes.. did the compression and leakdown test.. drove 20 miles fine... got very near empty which is not a normal practice!...got gas.. now have idle problem.
Havent driven since.
Any ideas?

Before you pull the head, check the injector on that cylinder.

A guy on another forum has an 89 that wasn't running right in one cylinder and it turned out to be the injector.

nize · nize's Garage

Quote:

Originally Posted by Luis de Prat

Before you pull the head, check the injector on that cylinder.

A guy on another forum has an 89 that wasn't running right in one cylinder and it turned out to be the injector.

he already performed a compression test and found one cylinder is down on compression. a bad injector wouldn't affect compression readings. it has to be one of these;
1) intake valve (unlikely, as they rarely fail)
2) exhaust valve (likely)
3) head gasket (likely)
4) piston rings (rare, but possible)
5) scored cylinder (rare, but possible)

i think the head must come off.

Luis de Prat · 12-23-2007, 04:53 AM

Quote:

Originally Posted by nize

he already performed a compression test and found one cylinder is down on compression. a bad injector wouldn't affect compression readings.

Well here's one recent case in which it did. Read for yourself:

low compression in one cylinder caused by faulty injector

Quote:

Originally Posted by nize

i think the head must come off.

You seem eager for the guy to pull the head before checking other possibilities. He hasn't even done a leakdown yet.

Marcone · 12-23-2007, 07:10 AM

not to upset anyone..but ..

I wrote above that i did the leakdown and we already know that its the exhaust valve..

whether its the spring or the actual valve is unknown so far tho.