5 GT Turbo F4Rt - hopefully the correct decision

[DaveL485]

Commonest issue with sump gaskets is overtightened bolts, the 21, for example, is 9lb/ft on each bolt....my torque wrench doesnt even go that low.

 

[Adey]

its not really a gasket on the f4r though, its a seal. it sits in a recess machined into the sump

 

[Mark Davis]

its not really a gasket on the f4r though, its a seal. it sits in a recess machined into the sump

Now I’ve seen it and you’ve said that I’m pretty sure it can’t be that causing the leak. I think I’ll find it’s the rear main seal.

 

[Mark Davis]

All set to crack on with the task at hand tomorrow morning.

I’ve got some decent sealants from Engine Dynamics as well as the rear main seal from Renault. I also purchased a new clutch alignment kit/tool as lost the last one I had.

Planning to get engine back in by end of weekend and pray to baby Jesus that it no longer leaks afterwards.

 

[Adey]

hopefully all goes to plan

 

[bloke]

have we mentioned the main bearing cap sealing? that or the seal being knocked in cockeyed are the two main issues after a rebuild.

 

[Mark Davis]

have we mentioned the main bearing cap sealing? that or the seal being knocked in cockeyed are the two main issues after a rebuild.

@bloke - I have had the main bearing cap seal explained to me but be useful if you could let me know your thoughts.

 

[Mark Davis]

Engine is out and on stand. Looks as if the rear main seal is the culprit, you can see where it’s seeping at the bottom, it then looks to be running down onto sump in the corner we had isolated it too.

 

[Mark Davis]

Fitting the cam pulley/belt cover this time round, just gave it a quick coat of high temp paint that I had lying around.

 

[Adey]

tidy job, fingers crossed the new seal doesn t leak too

 

[DaveL485]

Have you put a stainless bolt in that cover? It looks stainless - don't use those in load or stress points like suspension or engine mount points.

The alloys in steel that make it stainless also make it weaker (you never get something for nothing), they're around 75% of the strength of normal steel. Also when you connect stainless steel to steel/ally you create a small battery as they are dissimilar metals. Therefore the current flow takes away from the steel to corrode it more quickly than on it's own. Just because it's shiny doesn't mean it's good!
Stainless steel can also degrade after prolonged exposure to certain environments, in this case being salt and/or heat. Its called chloride stress corrosion cracking, and is basically where chloride ions get in between the metal grains to weaken them, which can then lead to brittle fracture of the material.

TL/DR: Stick with high tensile steel bolts for anything bearing load.

 

[Mark Davis]

Have you put a stainless bolt in that cover? It looks stainless - don't use those in load or stress points like suspension or engine mount points.

The alloys in steel that make it stainless also make it weaker (you never get something for nothing), they're around 75% of the strength of normal steel. Also when you connect stainless steel to steel/ally you create a small battery as they are dissimilar metals. Therefore the current flow takes away from the steel to corrode it more quickly than on it's own. Just because it's shiny doesn't mean it's good!
Stainless steel can also degrade after prolonged exposure to certain environments, in this case being salt and/or heat. Its called chloride stress corrosion cracking, and is basically where chloride ions get in between the metal grains to weaken them, which can then lead to brittle fracture of the material.

TL/DR: Stick with high tensile steel bolts for anything bearing load.

Jeez Dave, that’s some essay on bolt selection. It’s not load bearing, just a cover for cam pulleys.

 

[bloke]

looks like it's the cap, got to glue a couple of engines together tomorrow so will try and remember to get some pics for you.

 

[DaveL485]

Jeez Dave, that’s some essay on bolt selection. It’s not load bearing, just a cover for cam pulleys.

....that also receives the M10 bolts for the suspended engine mount. Why do you think it's held on with 4 or 5 M10 fittings and not puny M6's like most covers? To be honest that one on its own wouldn't matter too much, it was more to make the point for future reference when swapping out old bolts for new, you need to think about the bolt material and application.

 

[Mark Davis]

....that also receives the M10 bolts for the suspended engine mount. Why do you think it's held on with 4 or 5 M10 fittings and not puny M6's like most covers? To be honest that one on its own wouldn't matter too much, it was more to make the point for future reference when swapping out old bolts for new, you need to think about the bolt material and application.

Understood mate, all good knowledge.

 

[Mark Davis]

Managed to get a few hours during lunch today as working from home.

Took the sump off and have to say the OE sump seals look good and the one on there was brand new so I left it. Just cleaned up the sump itself and the block surfaces and refitted following the suggested sequence.

I sourced some decent sealant from Andy and ED. I used it on the end cap seals, using my torch you could see a gap on both sides so with any luck that’s all sealed up too.

On closer inspection I can see why the rear main seal was leaking, the bottom part had been pushed in too far meaning the whole seal on the piss just enough to cause the leak. I’ll remove engine from stand this week and fit new seal. Then put it altogether and pray to baby Jesus that it doesn’t leak.

 

[andybond]

Bloody frustrating that!

Who built the engine @Mark Davis ?

 

[bloke]

Did you pull the end cap off and clean the old sealant out from it?

 

[Mark Davis]

Bloody frustrating that!

Who built the engine @Mark Davis ?

Mark Galvin

 

[Mark Davis]

Did you pull the end cap off and clean the old sealant out from it?

No but he had sealed it ok, was leaking from rear main seal not end cap. I just added a bit more sealant down the sides as a precaution.