How do I diagnose a cracked engine block?

[DougR]

Hi Kim,

When you do the reinstall with a new/different liner be sure you measure piston height as detailed in the shop manual. This adjusts compression ratio / pressure and is important.

Regarding hard starting when cold, are you using the cold start device?

DougR

[KimSails]

Compass -- Thanks, I will ask the shop to check the liner. The used liner from Mark is on its way. I will hopefully be able to start reassembling next week.

I will try to measure the pistons on my own with basic dial calipers as best I can. The pistons are still in the engine. I did try to get them off to have the shop inspect them. However, I couldn't get the conrod bolts off. The manual specifies the torque at 65Nm / 47 ft lbs. Even if I can get them off with a breaker bar, I don't know that I can back get to that torque on assembly with the limited access that I have. So, I will leave the pistons and go ahead with the piston install method Doug R suggested.

Doug R -- I had thought that since the cylinder blocks sit on the shims, and the blocks are being reused, that the shim could be left in place (no change). I suppose, though, that depends upon the thickness of the liner shoulder and how the liner is fitted to the block. I will check, thanks.

Regarding the Cold Starting, as far as I know my engine doesn't have that. If it does, then I have no idea where it is at or how to engage it.

Separate question on the cylinder head nuts: the shop manual indicates that new cylinder head nuts should be used. The old nuts seem to have a red nylock or lock-tite material and it seems to be coming off on several of the old nuts. There are two cylinders, and each cylinder has 3 regular nuts and one tall one. The tall nuts are there to accommodate an engine lifting eye. A couple part websites suggest that the nuts should be replaced with a washer and a nut (a change in Volvo specification). The nuts cost about $20 each. Do I really need to spring about $200 for a new set, or can I buy a standard high-strength specification nuts (grade 10.9? grade 12.9?) and get a set for much less?

Thanks,
Kim

[mark maulden]

Be sure to have your shop clean the liner thouroughly. There are most likely remnants of the old seal still under the shoulder. I think the MD11 has a manual cold start device. You should be able to find it via the shop manual. Maybe PO never bothered to rig it.. My MD17 is automatic and works on oil pressure. All it is is a way to advance the injector pump rack further than normal operation. As for the nuts, are you sure those prices arent for the nylock nut? Talk to Marine Parts Express in Maine and see what they say. I also see no reason why you can't buy off the shelf steel nuts and washers..Removal of pistons fron the con rod should be rather easy. Big pin and snap rings. But if they aren't beat up, scored etc, just use them. Your check just arrived..

[mark maulden]

One other thing. I refreshed my MD17 six yrs ago and broke it in using Delo 100 wt oil and still continued to use it until two yrs ago. They quit making that oil two yrs ago and since I was broke in, I changed to Delo 400 30 wt. Last spring, i started it and bad things happened. Same thing happened this spring. Bent push rod and broken tappets. Some valves were stuck and full of carbon. Machinist said he's seen other occurances with older engines using newer oils and suggested oil additives. I went back to Delo 100 but switched to 40 wt..So, my advice is do not use high detergent oil. Especially during break in of "new" cylinder as the rings will not seat..

[KimSails]

Thanks Mark, I will have them clean the liner. The existing liners looked like they have surface rust on the outside. I will also have them press in the new liners with new seals.

Cold start -- I have read about it before, but never found it on my engine. I will look again. It should be easy to see without the cylinders and heads off.

After my last post here I did more googling about cold starting. I noticed some six-year-old posts on a different site that you had made about checking the shut-off release. I will check that my next time at the boat.

Cylinder head nuts -- both MarinePartEurope and VolvoPentaStore show the old nut (943414) replaced by a nut and washer (994130 & 930872). MarinePartsExpress doesn't specify the new parts, but does say that the old nut has been replaced by "multiple parts" and to call for info. So, I will call for info.

Pistons -- I did see the snap ring on Saturday and thought about trying it. But the manual indicates heating the piston to 100°C for assembly, so I figured the pin was pressed in and couldn't be easily removed. I will try it though if you think the pin will slide out. It can't hurt to try.

Oil -- I've been using Rotella 15w40. This is my fourth season with this boat. What in the oil coding indicates if it is a high-detergent oil?

Glad the check arrived early!

Thanks,
Kim

[DougR]

Hello Kim,

To speak to your questions:

- when you get the new(used) liner, measure the thickness of the flange on the top of the liner and compare that to the thickness of the flange on the old liner. It may be that there will be no need to adjust the shim thickness....

- The purpose of the red plastic under the head of the cylinder head nuts is two fold: 1. To act as a lock washer and prevent the nut from loosening & 2. To act as a seal for those two nuts that are located under the valve cover.
Without the red plastic you will have oil leakage under the two nuts and down the exposed cylinder studs. I rather think you can use a lock washer under the external nut, just like under the long nut, or an aftermarket equivalent nut. The nuts under the valve cover will need some sort of oil seal washer.

- The cold start on the MD 11 is a small brass spring loaded button immediately adjacent to the high pressure injection pump on the engine timing case. To operate it you give the engine about 1/2 throttle and push the button down. The button should stay down until the engine starts, at which time the governor will allow the button to pop back up. There was a bracket kit which allowed the button to be remotely activated by a pull cable, and there was even a solenoid which activated it electrically. When activated, the cold start mechanism allowed the fuel rack to go further than normal " full throttle" and thus injected more fuel than normal. It also retarded injection timing several degrees to place the injection point closer to TDC for higher heat and more compression.

If you have been using Rotella 15/40 it's probably fine to stick with it.

DougR

[KimSails]

Thanks Doug, I will make sure to measure the liner. After talking with Marine Parts Express I broke down and ordered the nuts and washers for $169. They didn't know if there was anything special about either the nuts or washers. I will take a look and also talk with the shop. I might use them or return them and use something more standard.

Found the Cold Start!! I can see why Volvo made it automatic on the MD17 and with an optional control on the MD11C. It is a real pain to get to for something that is used everyday the engine is started.

I took out the a snap ring from the piston/conrod pin. It looks like the pin rotated with the piston and it did not slide out of the piston (apparently the pin is pressed into the piston as suggested in the manual. I reinstalled the snap ring and will leave the pistons in the engine for assembly. Time to rent or buy tools for piston ring installation and a pliers-type ring compressor.

[model 10]

You are not going to have any luck cleaning those ring lands without removing the piston. There is going to be a ridge of carbon on the pin between the piston and the the rod, so use a piece of wood dowl, a hammer and the heat gun.

[Compass790]

Measuring the piston with a caliper will be fine. I would have bought ordinary nuts & put nylon washers underneath or used Loctite master gasket under the nuts to hold oil in but I'm not familiar with your particular engine model.

[KimSails]

Guy -- I have a heat gun and can try that. Do I need to be concerned that the inherently uneven heating of a heat gun might distort the lower part of the piston enough to cause an issue? Or that banging on the pin could damage the crankshaft journal or bearing surface of the conrod through the leverage applied from the pin down to the crankshaft? Or should I expect that just a little heat and a few light taps should be able to get the pin out?

Compass -- I may still use ordinary nuts. I want to talk with the diesel shop and also take a look at the incredible $20 nuts.

[model 10]

You are not going to distort a diesel piston with a heat gun. You do need to support the piston and rod while you are beating on them. You can make a puller with some all thread and a deep socket / block of wood etc. You only need to get the pin started, then it should move more easly.

[Sailorbob8599]

Originally Posted by Guy

You are not going to have any luck cleaning those ring lands without removing the piston. There is going to be a ridge of carbon on the pin between the piston and the the rod, so use a piece of wood dowl, a hammer and the heat gun.

Forget the hammer . . . use a puller of some kind (easy to make one with threaded rod). A hammer in the hands of a non-professional can only create more problems & grief!

[KimSails]

Guy and Sailorbob, the puller idea worked a treat! The piston pins came out with little trouble. I added a little heat with a heat gun, but I don't know that it was necessary.

The replacement liner from Mark should arrive tomorrow. Hopefully I can get it reassembled and running next week!

[Lepke]

Originally Posted by farmall.dude

Actually, I don't think that's true. I know some NASCAR (amateur division) folks that are always looking for marine engines. They're built to tighter tolerances because they run at high RPM constantly. Or so I'm told...

Actually we used marine engine heads in classes that required cast iron because they have bigger water passages and cool better. Most marine engines pass thru the same line as auto engines and have the same machining. Some manufacturers make special engines based on a production engine, but just for racing. Like the Chevy 350, etc.

[KimSails]

An update for anyone who might be interested...

I successfully started the reassembled engine yesterday. It seemed to start and run well for 5 minutes. It clearly would have run longer, but I shut it down because I saw two issues to correct:

-- A leak at one injector on the fuel return line
-- A leak at the water pump on the pump outlet side

I tightened the fuel return bolt and ended up breaking off the bolt head, with the bolt body stuck in the injector. I picked up an "easy-out" today. I will try to remove the rest of the screw tonight. I've ordered a replacement fuel line bolt and copper washers (plus a few extras of each). They will hopefully get here before the weekend. So, waiting for that before I can test the engine further.

The water pump connection is one that I don't understand. If anyone has a connection like this before (photos attached -- not great, sorry), I would appreciate some advice. The connection is between the pump and what looks to be an original, engine-specific copper or bronze tube. The tube seems to simply fit into the pump outlet with just a little rubber washer. I don't understand how that can seal (but it did, previously). Now I don't know how to get it to re-seal.

I checked the engine oil after the few minutes that the engine ran. The oil still looked perfectly clean (no water, no milky color, no froth). This is the original issue with the engine. A few minutes is not a real test, but hopefully a positive sign.

The reassembly was delayed by a week with a cylinder stud issue. The threads on the top of one of the cylinder studs were damaged. The nut got stuck trying to get it on the stud threads, and the stud unscrewed from the block trying to remove the nut. I ended up cutting about 1/4" off of the stud to get the nut off and clean up the threads. The stud was reinstalled with about 1/8" less in the block and the same amount less in the nuts. Even with the shortened stud, there seems to be more thread contact with the replacement nuts (about 1/2" tall) than there was in the original nuts and more thread contact in the block than there is in the nut. If this holds for the remainder of the season, I might replace the stud in the winter if I can find a good used replacement. I don't think they are available new.

Thanks,
Kim