wopfe

Hi all,

Did a compression test today after about 20 min drive with my '79 manual 4.5 euro spec. Friend pushed both accelerator and clutch and cranked for 5 sec per cilinder:

135 bar - 138 bar
140 bar - 141 bar
148 bar - 138 bar
140 bar - 140 bar

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Front car.

Cheap **** tool, but what do you guys think? I think its low but quite steady for a 39 year old car.

This was meant as a 0 test. I am going to pull the engine for waterpump, timing belt and PK tensioner install. Also a head gasket renewal due to small oil leak on the driver site of the car. Any advise let me know (and yes i am watching https://rennlist.com/forums/928-foru...the-heads.html close )

StratfordShark

I don’t know the earlier cars well so the numbers are lower than I’d see on my S4 with higher compression head, but the pattern and range looks good.

Bit I think you measured psi and not bar - those pressures could synthesise diamonds!

Mrmerlin

the numbers look pretty consistent and pretty close,
the BAR reading doesnt make sense might you mean PSI?
IIRC the 79 Euro was the lower compression version.

The reason i would be installing new head gaskets would be to replace the originals due to old age.

the oil leak you are describing is most likely coming from a cam tower base gasket or rear cam tower cover.
So a head bgasket change will not fix those leaks.

Roger has new silicone rear cam tower seals and Greg Brown cam tower gaskets.

Your early car will also require the new gasket to be trimmed,
watch out for the lifter liner gaskets they have very thin figure 8 gaskets,

if you dont manage the thin gaskets properly then the 8 gaskets will also go on the new tower gasket this will unseat the tower and you will have oil pouring out the edge closest to the V.

NOTE use a feeler gauge to make sure the top edge of the tower is clamped down to the head before you fit the belt.

wopfe

@Mrmerlin @StratfordShark thanks for your quick reply.
I guess you are right with the bar....its psi...
I want to order a set of "engine gaskets", i will replace everything. How would i manage them right? What do you mean with the note? I want to first replace the front end: waterpump etc and after that start with the top....

SwayBar

Your numbers are perfect.

You can ignore the 148 psi cylinder and see it as 140-ish.

Mrmerlin

The early cam towers have lifter guides, these are metal collars that hold the lifters, they are slid into the towers, and have very thin gaskets
the later engines just have bores machined for the lifters, and do not have these figure 8 gaskets.

The early lifter guides have a gasket that looks like a figure 8 outline.

NOTE the 8 gasket is paper thin and can be missed,
this gasket combined with the cam tower gasket can cause an unseating to occur.
OR added onto the lifter guide without removing the old gasket because you didnt see it!

What happens is the combination of the gaskets will prevent the cam tower from fully seating down,
thus the inner edge of the tower ( closest to the V) will not fully clamp down the tower gasket,
and then oil will run out of the inner edge of the gasket and fill the V with oil..

Essentially you have to know what your doing with all of the gasketing ....

so you remove the old 8 gaskets and fit new ones.

Also trim the new tower gasket so it wont get caught under the lifter guides.

Check your work with a feeler gauge placed along the top and bottom edge of the tower to head area to see if it slides past the gasket,
if it does then the tower will leak.

This check is done after the tower has been properly tightened.

wopfe

@MrMerlin, got it thanks for the further explanation! @SwayBar thanks for the reply.

SeanR

Consistency is what you are looking for, and you have that.

wopfe

Thanks for the reply!