302 SBF coolant leak, any opinions?

[Julian West]

I'm looking for a second opinion. I filled my car with coolant for the first time yesterday. As I was checking for leaks I noticed a small pool of water building on top of the timing chain cover.

The water seems to be seeping from between the block & the timing chain cover.

All my instincts point to the timing chain cover/engine block gasket. Has anyone any experience of this?

If it is a simple gasket failure, how much work is involved in removing/refitting the cover? Does the sump have to come off??

Thanks on advance for any opinions!

[Alex Hirsbrunner]

Hi Julian,

The sump does not have to come off. You will however, need to cut the oil pan gasket off at the block. The replacement timing cover gasket set will come with a replacement for what you cut off. I would check carefully for any erosion of the gasket surface (if it's a used part).

Regards,

Al

[Tim Kay]

I had a leak one time that collected water in the same area I initially was worried it was the timing cover and really did not want to remove all that while in the car. Turned out to be the inlet water line flange, that bolts to the intake manifold, was warped.

Replaced the gasket and it still leaked. I had to re-surfaced the flange flat. It was a pin hole on the underside of the flange where you could not see but if you swiped your finger under it you could feel the moisture.

FWIW, if you don't already have one, buy a water pressure test kit. With that you can test for water leaks without running the motor. This little episode got me to buy one. It's a great addition to your arsenal of tools.

[MICK.]

Hi Julian its a shame your not local to me as i could pressure test it for you
if your carefull you can remove the cover without breaking the sump gasket best of luck.
Regards mick.

[Jac Mac]

Julian,
Hope you have not pulled the front cover yet, that coolant is coming from higher up, either the t/stat housing to manifold or the intake manifold /cyl heads.( Looks like a bit of brown stain on that LF corner of manifold but that may be sealant). Could also be a small leak from top rad hose or bypass that is tracking down but those usually pool in the recess on RHS. If it is the manifold gaskets , trial fit the manifold without the valley seals( just sit in place with hand pressure) and measure the valley gap. Use valley corks/gaskets of that measurement in thickness, when tightened down it will compress this enough, some gasket sets supply valley seals that are too thick which prevent the manifold from sealing properly at the water crossover points.

Jac Mac

[Julian West]

Thank you Gents, I appreciate your opinions. I have'nt pulled the cover off yet & hope I don't have too!

I've mopped up the puddle & watched it re-fill several times & it's not immediately obvious exactly where the water is coming from....

I'll see if I can rig up some kind of pressure test before I get the spanners out.!!

[Howard Jones]

I did replace the gaskets on the water-pump and the timing cover with the engine in the car. I too have a GTD. You will need to remove a couple of pan bolts in the front and loosen the pan so that the timing cover will clear the front of the pan where it seals against the timing cover, but the pan does not need to be removed completely if you don't hurt the gasket. You will also need to remove the dampener. The GTD's also have that crossover engine mount that is in the way but if you remove it you can't hold the motor up and drop the pan easily. All the stuff you just took off is much easier to put back on correctly with the motor on a engine stand.

If I ever did this again I would pull the motor/gearbox out as a unit, remove the gearbox, and fix the front cover issue whatever it is with the motor out of the car and on a engine stand. Then you can insure that everything goes back together with good tight seals, clean and correctly fitted. Either way it's a all day deal. My way is more work but a lot less frustrating. You can also do some maintenance on the input shaft bushing, CV joints and clutch while you are at it.

This is one of those things that each person thinks is easier to do one way or the other. I personally hate working on the front of the motor from inside of the car. The only thing I hate worse is trying to put on a pan gasket/end seals/pan laying under the car on my back with the car 2 feet off the ground on jack stands.

The good news is I think it's a bypass hose or thermostat housing leak. Maybe one of the bolts that go through the waterpump is loose. Thus the rust (from the steel bolt).

You can however remove the waterpump without removing the timing chain cover and anything off the bottom of the motor. This might help you isolate where the water is coming from if the stuff on top, intake, hoses, and thermostat, are all OK.

[Julian West]

Thx Howard,

FWIW I fabricated engine mounts for my GTD that allow me to remove the sump without pulling the motor.

I've double-checked the water pump bolts and the timing cover bolts (that I can see) but I haven't checked the thermostat housing or the bypass hose... YET!!..

[speed220mph]

Julian: You didn't say whether or not you ran the engine. If you did and before you start pulling things apart, sop up the coolant laying in the timing cover, then put some Aluma Seal in the coolant. Run the engine for awhile after it gets up to running temp. This may seal the leak. Also, don't assume the leak is between the front cover and block. It could be from one of several other locations above the cover such as the bypass hose, radiator hose, thermostat housing cover or manifold and head. This may seal the leak. If you didn't run the engine, snug all the bolts, being careful not to over-tighten them. Check for leakage again, then do as I described above. Uh, did I say pray, too?

Good luck.

[Julian West]

Thx Speed220,

I bought the engine s/h after I saw it running in a cobra, & it's has now been sat un-started for 3 years odd. I suspect the leak came with the engine & I just didn't spot it.

Can you tell me any more about Aluma seal?

[Bernard]

As you say Julian coolant leaks in this area are frequently coming from the distribution cover. Several reasons can be at the origine of this problem:
- poor watertightness due to the aluminum cover sealing surface corrosion (old liquid cooling was without inibitor)
- poor watertightness due to a tired bolt thread(s)
- distribution cover flatness problem due to overheating
To solve the point you have to check the distribution cover sealing surface. If it is not clear and right, bring it to the workshop for honing operation. It could be a good opportunity to check that both cover faces are parallel (that is not always correct) and to machine a groove to install a O ring. If it is not necessary to go to the workshop (may be you are lucky ) you can install an additional washer made of fine paper at each water passage (in front of the gasket) to be sur that the tightness will be more efficient in this area.

[Julian West]

Gentlemen,

Thank you all for your advice and opinions, I'm grateful for you all taking the time to post. You've all helped me solve the problem!!

The coolant was weeping from where the temperature sender threads into the inlet manifold! I removed the sender & the adaptor, cleaned the threads & then re-fitted with some thread sealant & cured the problem..... )

I discovered the source of the leak very quickly after I made a basic pressure test kit. I simply connected some 10mm rubber hose to the expansion tank nozzle that feeds the 'puke tank'. I put a tyre valve in the other end of the hose & connected a foot pump.

I only needed to put around 2-3 psi in with a footpump & the leak was obvious. The pressure test also allowed me to carefully check the rest of the system, and to leave it pressurised at up to 10 psi so I could give the whole system a longer term test.