F360 engine head: gasket change + water leak? Low pressure in cylinders

Well...

If during your mechanics testing he has discovered two cylinders that have reduced compression numbers then he may have found something. He would have discovered that by performing a compression test. Now at that point he should do a "leak down" test that will give him another indication and much better pin-point the issues (if any) with those cylinders. It does that by sensing if you have compression escaping from either the valves, or past the piston rings. That would be what I would ask him to verify.

Now to your questions:

1. AUDIO: A small pop sound, like a tiny backfire, SOMETIMES, when I let my foot off the accelerator pedal. (pretty normal by sports car standards)

2. VISUAL: I can see the engine connection shake and is not running smooth. Something in the ignition/combustion could be toned. (Without seeing this I would guess that either its fine & minor, or the two effected cylinders are contributing to the shake).

3. SENSE: At idle, inside the car, yup, I can feel the car sometimes not being static. I can feel the engine behind me not being absolutely 100% still. Perhaps a 10% shake is sensed. (again, it could be normal, or you could be feeling the two down cylinders).


Why am I asking all this when I know I am going to perform the engine out?

1. I want to know what you guys recommend I order for safe measure since I am removing the engine cover and exposing the head. Gaskets, and ... ? (during a major you do not expose the head gaskets. Please understand that to expose the head gaskets is a huge undertaking. Cars go their whole lives without ever exposing their head gaskets).

2. I want to UNDERSTAND my motor. (that could take a lot of teaching as I have done this for 30 years and learn new things daily).

Thanks in advance.

 

My 430 acted up recently. It was intermittent at first, then things got more extreme.

Had cel lights several times, a few backfires, some shaking, loss of power at times, etc


Turned out to be cracked headers. I would check this before pulling your engine!

 

What year is your 360?
How long have you owned the car?

 

Hi Mowater,

Taking the head off to replace the gasket is a fair bit of work to do. You mentioned loss of coolant? (water trickles down to the valves). Have you measured the rate of loss? I would suggest filling the expansion tank to say 5cm below the neck of the filler cap and taking the car through a few heat cycles and drives and then re-measure to see if there is in fact a loss. Suggest you don't fill any higher than 5cm as otherwise your loss could be to the overflow pipe and you'll think you have a loss when probably you don't.

Do you know just how low the compression is? A fit car will have a nice tight bunching of numbers for all cylinders. Often people get readings in the range of 160 +/- 10 psi from motors that feel perfectly fit and fine. I understand that a really good result is closer to 200 psi with no more than a 5% spread. The numbers often seem to vary but it's important that there be a good tight bunch of numbers.

If you do have bad compression the next step is often to do a leakdown test which measures the cylinder's ability to hold pressure over a given period of time. This test can help identify if the problem relates to the piston rings or the valves or other. This test might also show signs of coolant being forced out of the head or air into the coolant system, both of which would confirm problem with gasket.

If you are taking the engine out you probably should replace the main gearbox bushing as it does wear faster than most of the other mounts. Perhaps the engine mounts also require replacement.

I wouldn't be too scared to drive the car. If you keep a close eye on your coolant temperature and level and also examine your engine oil for traces of contamination you should be ok.

 

Sure, the Tubi could be giving you the sound you describe.

Absolutely.

The head gasket can be subjected to corrosion if the car has not been maintained well, or has been abused again & again perhaps exceeding its holding capacity. However these cars are robust and can put up with lots of hard use. But... If the coolant has not been changed regularly that alone could have contributed to fatigue of the head gasket and a failure of the seal between two cylinders during an extended storage period.

The computers on this car will not pick up a low cylinder reading per-say. But they will pick up a foul reading BECAUSE of the low cylinders as the fuel trim and or 02/converter readings will be skewed if its serious enough.

A major will not take care of cylinders filling with coolant. The original reason why your tech said not to drive the car is that he feared hydro-lock (where a cylinder fills with fluid and then you crank it over giving no place for the fluid to go - therefore things like connecting rods and valves get bent). If indeed the coolant is filling the combustion chamber you will need to remove the head to diagnose the issue with the gasket.

Understood

As I see it you should get the compression readings and post for us to see if you would like. Then proceed with a leak down test again posting for us to see results. At that point you can formulate a general impression with your tech and follow the procedure that makes you happy.

My initial impression is that if you are driving this car without concern or malady that you may just need a regular full service and then continue to drive happily. Confirming the pressure readings would help with that assumption.

 

A few suggestions here:

If owning the car for just (3) days, if I read that correct, I would do whatever it takes to get that car back to the seller for a refund. That would indicate you purchased a vehicle with a known problem and the seller wanted to dump it on someone else. (If that was the case). I know that "refund" sounds like a small word but, the ultimate cost here, if in-fact you have a head-gasket issue not a small task. Not only do the heads get pulled, but, you really want someone that knows how to do this work and fully check the head as-well. The damage could be (sure) just a head-gasket, but, could also be the head itself.

On the water loss side. If you did have a bad head-gasket, the water is taken into the cylinders which is below the valves. The head gasket position is between the cylinder block and the head assembly, not from above. (If it were from above you would have a much more serious issue then such as a defect in the head itself, crack of sorts from a critical overheating issue that may have taken place)

Typically when you loose water with a bad HG, on your intake stroke (piston downward, intake valves in open position), not only are you taking in fuel/air mixture but in this case water leaking into the cylinder area from a bad what-I-call fire ring that surrounds the cylinder bore itself. It "burns" with the mixture, you'd see some form of condensation/smoke from the exhaust (with a sweet smell possibly). Additionaly a HG leak would also (possibly) cause your overflow tank to rise quick because, on the compression stroke (piston up, valves closed) the compressed mixture would attempt to force its way back into the water system. The mechanic can check for this with a pressure gauge on the overflow tank.

 

I don't know about the other stuff you're asking about, but the occasional small backfire/popping sound you may hear when lifting off the gas is normal, and more easier heard with a Tubi vs. stock muffler. Mine does that sometimes (as you say, it's inconsistent- not every time I lift my foot off the gas), and I'd like to add that I love the sound of it when it does happen!!

 

My opinion: Send it back. A blown head gasket in an all aluminum motor could potentially be catastrophic. A major service is not going to fix this, or any other cause of two cylinders having low compression. I cannot see cracked headers causing low compression either. Head gasket, rings, valves, warped head, scored cylinder wall - these are the things I think about when I think about low compression. Just thinking about this is making me ill.

 

From your presented information; You do not have an issue. All symptoms seem about normal, the shake could be anything from motor mounts to plugs or Coil over packs. Head gasket failures usually dont cause shake from fouling because the mixture loves water (in small amounts). Ever heard of water injection.

If you have a major head gasket leak the symptoms will include:
a. Water in oil (sometimes)
b. White smoke at startup and maybe while driving. (almost every time)
c. Coolant loss, i.e. the coolant tank level will drop. You can measure this yourself. (every time)

I do agree better safe than sorry; here is my list:
1. Post compression numbers from your mechanic
2. Have mechanic complete leak-down test, very standard procedure. Post results here.
3. Check OIL for water.
4. Measure coolant level, drive, let idle, temp cycle a few times, remeasure level. If its about the same you are at no risk of hydra-lock.
5. Get a second opinion from a recommended Ferrari mechanic, maybe a dealer. Its a small price to pay when comparing to an engine out repair.

The F360 has many normal failures (weak spots), head gaskets are not one of them.

If it were my 360, I would just drive it and keep an eye on coolant levels, exhaust at cold start (have someone else start it), and see if the symptoms progress. An engine out head gasket repair is so expensive, your risk/reward is looking good.

Good luck, and most importantly keep this thread updated!

 

Low compression in two cylinders = no issue? Yikes!

 

Trent is IMHO 100% spot on. I would follow his advice....

 

Hmmm lots to consider.......

Your coolant temperatures seem to be fine - very much same range as my own 360 which is also calibrated in degrees C

You don't appear to be loosing coolant - good.

Your mechanic may have done compression test (which is relatively easy and quick to do) and not done leak-down (which takes longer and is a little more complex). If he did do the compression test, he really should have made a record of all the values and be able to give them to you.

I'd say go ahead and book the car in to have the main service done but tell them that you want your compression tested first and if it's bad tell them to give you the results and post them here before they carry out further work. There's absolutely no point doing a belt change, oil change, major and then having to come back and split the engine a few months later.

The gearbox mount is pretty easy to diagnose. You can visually inspect it and if it's way gone (like mine was) it's pretty obvious. Another tell-tale would be if the exhaust tips aren't nicely centred in the outlet through the rear bumper. The gearbox mount number is 186698. It's really easy to replace if you have the gearbox off the car, quite a bit harder with it still in there but very possible. Here's a link to my DIY thread.....http://www.ferrarichat.com/forum/showthread.php?t=331587&highlight=diy+gearbox

Best of luck and keep us informed!

 

You sir are a pleasure to work with. Best to you.

 

I have a set of heads sitting on my garage just in case.
I sent it to get cleaned, port and bore. The change all the valves seals abd check all the valves just to be perfect. It includes the complete head, I mean camshaft ect. Just take yours out and install the new ones.

 

1. I suggest that you get a second opinion

2. My cars back in the UK spend about 10 months a year in storage while I'm in Dubai and this has been happening for the last 3 years. The only issue I have is batteries, servicing and flat spots on the tyres. Apart from that every summer when I'm back in London they run perfect. You say that your car has not been used for 6 months only which as far as I'm concerned is not an issue whatsoever.

3. Changing head gaskets and skimming the heads is a lot of work so just make sure that you actually need to have that work done. It is difficult to diagnose something online but I don't think that you actually have a head gasket problem.

Regards

 

Ok. I will post pictures when I get home. The heads came from a spare engine I bought. You always need new head gaskests when you remove the heads(just be safe).

 

Ahh! This might be a different problem. Are they saying that they found coolant in the spark plug recess / ope? As per this video.......?

[ame]http://www.youtube.com/watch?v=ynjuzYuzQrc[/ame]