Bottom end rebuild - what am I in for?

Bottom end rebuild - what am I in for?

Author
Discussion

richardmadden

Original Poster:

38 posts

42 months

Wednesday 7th October 2020
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Hi all,

Having taken the oil pan off to investigate low oil pressure, my respected specialist says that my Griff 500 is likely to need a full bottom end rebuild. Apparently there's lots of wear.

They did the top end a couple of years ago so hopefully that won't need any work.

What do you think I might be in for £ wise?

Any recent comparable experience would be welcome.

Thank you!

citizen smith

629 posts

145 months

Wednesday 7th October 2020
quotequote all
Are the mains and big end bearings down to copper. Has he even taken the crankshaft out to measure the wear using his Micrometer on the Mains and Big End journals of the crankshaft.

Has the crankshaft previously been reground.

It's basically how long is a piece of string.

The old saying many moons ago was, that if you did a top end recondition without doing the bottom, then the bottom end would wear out quickly.

richardmadden

Original Poster:

38 posts

42 months

Wednesday 7th October 2020
quotequote all
To his credit, he hasn't got near quoting yet as he hasn't done all the due diligence you suggest. I know he will - he's a good guy.

I was just wondering whether I'd need to sell one kidney or both, but as you say, it's too soon to know.



Englishman

2,039 posts

174 months

Wednesday 7th October 2020
quotequote all
Yes, you need to see the damage, but a full rebuild from Dom is listed as £4K+VAT ( http://www.powersperformance.co.uk/upgrades/5L-REB... ). Assuming you can halve that just for the bottom end, then add the engine out/in costs you get to something like £3K+VAT as a ballpark.

richardmadden

Original Poster:

38 posts

42 months

Wednesday 7th October 2020
quotequote all
One and a half kidneys then...

Hey ho. I'll keep you posted.


phazed

19,542 posts

168 months

Wednesday 7th October 2020
quotequote all
Maybe go for a V8D short engine.

Chuggaboom

1,144 posts

212 months

Wednesday 7th October 2020
quotequote all
richardmadden said:
Apparently there's lots of wear.
Perhaps it would help (PH) if you described what your specialist has found/said ??? wink

Boosted LS1

19,686 posts

224 months

Wednesday 7th October 2020
quotequote all
I expect it'll be a couple of hundred quid to regrind the crank if required plus new shells plus labour. If the bores need a hone then you'll need new rings, another couple of quid or so. I'd be very surprised if your bores needed reboring and new pistons. if so, new engine time.

QBee

18,076 posts

108 months

Thursday 8th October 2020
quotequote all
As he has already done the top end, ask him if he can do the work without removing the engine from the car.
It ties up a ramp, but I believe it is possible.

Then you are just into new bearings and shells, and a crank grind, plus of course the labour and fluids - hopefully.
In which case it won't be earth shattering, but will be between £1k and £2k. The parts aren't expensive, but there is the cost of the re-grind (couple of hundred quid) and the labour and VAT. To be fair to your guy, it is easier to work on the engine on an engine stand because you can turn it upside down to work on it.

My TVR specialist did the top and bottom ends of my 4 cylinder Saab engine without removing it from the car, but he much preferred to do the bottom end of my RV8 out of the car.

blaze_away

1,190 posts

177 months

Thursday 8th October 2020
quotequote all
As others have said it really depends on what is in need of work.

If you cant swallow the cost of engine out and bottom end rebuild then........

What are the compression readings, has it been done yet ?

If its good (and as top end is done you can probably rule that out of the equation), it implies the bores/rings/pistons are in good order. That being the case you are left with bearings as wear points.

Replacing mains and big ends can be done engine in situ, although gearbox out for rear main.

If he suspects little ends then crank can still be removed engine in situ and pistons removed from below.

phazed

19,542 posts

168 months

Thursday 8th October 2020
quotequote all
For ease of working on the engine and therefore reducing time costs it is better to remove the engine.

blaze_away

1,190 posts

177 months

Thursday 8th October 2020
quotequote all
phazed said:
For ease of working on the engine and therefore reducing time costs it is better to remove the engine.
Yep fully agree, I wouldn't want to do it engine in situ. Too much dirt and awkwardness, lots of neck ache I suspect

Belle427

5,192 posts

197 months

Sunday 11th October 2020
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May just need a bearing refresh, mine on a 400 were showing signs of wear at 80000, ok it’s not a 500 engine but don’t jump to conclusions.

richardmadden

Original Poster:

38 posts

42 months

Sunday 11th October 2020
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Thanks all. If nothing else, TVR ownership really educates you about how internal combustion engines work. And I don't just mean the theory!

Classic Chim

10,871 posts

113 months

Sunday 11th October 2020
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Belle427 said:
May just need a bearing refresh, mine on a 400 were showing signs of wear at 80000, ok it’s not a 500 engine but don’t jump to conclusions.
This
If you have shell wear you’d expect some on the crank but not necessary so dropping the sump and checking tolerances must be the way to go after a compression test as mentioned above. Sometimes a mechanic can just hear it and he knows roughly what’s the score so if bottom end rebuild was the basic prognosis I’d expect if this is a tuned Tvr ear listening he”s probably right.

ETA I should have read your post properly O/P smile
Lots of wear!
For some perspective my low mileage 450 engine had shell wear at 48,000 miles mostly put down to old oil not being changed often enough or hard acceleration before oil was upto temperature.
I had a regrind as part of a rebuilt engine off Dom 10 years and 25,000 miles ago, still sweet thumbup

Edited by Classic Chim on Sunday 11th October 11:10

Zener

17,760 posts

185 months

Sunday 11th October 2020
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If the engine is worn I wouldn't build up in situ, you need to remove to de-bung the oil galleries and clean correctly otherwise your going to jeapardize the whole rebuild , often many years of accumulated silt and containing abrasive failed cam lobes etc all there , filters don't stop minute particles sadly

Boosted LS1

19,686 posts

224 months

Sunday 11th October 2020
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Sending the filter off for analysis may be useful in determining if the bearings are worn. Low oil pressure isn't always caused by bearing wear.

phazed

19,542 posts

168 months

Sunday 11th October 2020
quotequote all
I had low oil pressure on two occasions.

Firstly when a camshaft bearing decided to exit the block and spin around the camshaft. -10 psi

Then when the crankshaft broke near the first journal but still revolved with just a little bit of vibration! -10psi.

Don’t you just love RV8s!

QBee

18,076 posts

108 months

Sunday 11th October 2020
quotequote all
phazed said:
I had low oil pressure on two occasions.

Firstly when a camshaft bearing decided to exit the block and spin around the camshaft. -10 psi

Then when the crankshaft broke near the first journal but still revolved with just a little bit of vibration! -10psi.

Don’t you just love RV8s!
I remember you being 10 psi'd off after the second one happened.
If I remember it broke in Snowdonia, the day before a track day at Angelsey, with your better half in the car too.
Apart from the wind all the way from Nova Scotia blowing straight through the garage, it was a fun day.
Just a shame it was without you.




phazed

19,542 posts

168 months

Sunday 11th October 2020
quotequote all
Yes, that is correct. Such a shame after making the journey. It happened at a steady 50 mph in top gear!

Coincidentally, the camshaft bearing fell out as a track day at Cadwell Park.

These two instances where nothing to do with track days. It seems That the crankshaft wasn’t balanced well initially as my replacement made the engine much smoother. As for the camshaft bearing that decided to leave it’s home, it was one of the early split bearings and not one of the later fully spherical machined bearings. I will say no more......